Preseason Training: The Effects of a 17-Day High-Intensity Shock Microcycle in Elite Tennis Players

Preseasons in tennis are normally reduced to 5 to 7 weeks duration, and coaches should use an integrated approach to conditioning and skill-based work. The aim of the present study was to investigate the effects of adding a high-intensity training (HIT) shock microcycle to the normal training content in several physical performance indicators in the preseason training of high-level male tennis players. Over 17 days, 12 male tennis players performed 13 HIT sessions in addition to their usual training. Physical performance tests (30:15 intermittent fitness test [V_IFT], 20 m sprint, countermovement jump [CMJ], repeated sprint ability [RSA]) were conducted before (pre-test) and 5 days after the intervention (post-test). After the shock microcycle, results showed a significant increase in the VIFT (p < 0.001; Large ES) and a significant decrease in the mean RSA time (RSAm) (p = 0.002; Small ES), while there were no significant changes in the other parameters analysed (e.g., 20 m, CMJ, best RSA time [RSAb]; percentage of decrement in the RSA [%Dec]). Moreover, the training load (TL) during tennis sessions was significantly higher (p < 0.01; Large ES) than the TL during the integrated sessions, except during the first training session. A 17-day shock microcycle (i.e., 13 HIT sessions) in addition to the regular tennis training significantly improved parameters that can impact physical performance in tennis. Moreover, additional sessions, including running exercises based on the 30:15ITF and on-court specific exercises, were characterised by significantly lower TL than tennis-training sessions.

Key points

• HIT shock microcycle increases performance in professional tennis players in a short period of time.
• The inclusion of additional sessions, with running exercises based on the 30:15ITF and on-court specific exercises, was characterised by a significantly lower TL than tennis-training sessions alone.
• Coaches should be aware of TL (e.g., RPE) and fatigue-related parameters (e.g., muscle soreness) in order to avoid overreaching symptoms.

Key words: Block periodisation, high-intensity training, intermittent fitness test, repeated-sprint ability, rate of perceived exertion     

Short-Term Perceptually Regulated Interval-Walk Training in Hypoxia and Normoxia in Overweight-to-Obese Adults

We compared the effects of short-term, perceptually regulated training using interval-walking in hypoxia vs. normoxia on health outcomes in overweight-to-obese individuals. Sixteen adults (body mass index = 33 ± 3 kg·m^-2) completed eight interval-walk training sessions (15 × 2 min walking at a rating of perceived exertion of 14 on the 6-20 Borg scale; rest = 2 min) either in hypoxia (FiO₂ = 13.0%) or normoxia during two weeks. Treadmill velocity did not differ between conditions or over time (p > 0.05). Heart rate was higher in hypoxia (+10 ± 3%; p = 0.04) during the first session and this was consistent within condition across the training sessions (p > 0.05). Similarly, arterial oxygen saturation was lower in hypoxia than normoxia (83 ± 1% vs. 96 ± 1%, p < 0.05), and did not vary over time (p > 0.05). After training, perceived mood state (+11.8 ± 2.7%, p = 0.06) and exercise self-efficacy (+10.6 ± 4.1%, p = 0.03) improved in both groups. Body mass (p = 0.55), systolic and diastolic blood pressure (p = 0.19 and 0.07, respectively) and distance covered during a 6-min walk test (p = 0.11) did not change from pre- to post-tests. Short term (2-week) perceptually regulated interval-walk training sessions with or without hypoxia had no effect on exercise-related sensations, health markers and functional performance. This mode and duration of hypoxic conditioning does not appear to modify the measured cardiometabolic risk factors or improve exercise tolerance in overweight-to-obese individuals.Key points

• We compared the effects of a 2-week (8 sessions) perceptually regulated interval-walk intervention in hypoxia vs. normoxia in overweight-to-obese adults.
• Despite stronger hypoxia-induced physiological stimulus – yet essentially similar walking speeds – during training, psychological and physiological measures did not differ either between conditions or across sessions.
• Hypoxic conditioning does not appear to ameliorate exercise-related sensations, cardio-metabolic markers and functional performance, at least over a short training period.
• Adherence to exercise for longer than a 2-week period is likely required if the beneficial effects of exercise in hypoxia vs. normoxia are to be realized.

Key words: Obesity, hypoxic conditioning, perceptually regulated exercise, cardio-metabolic health, interval training     

Balance Training Exercises Decrease Lower-Limb Strength Asymmetry in Young Tennis Players

The issue of functional asymmetries in the lower-limbs has been the subject of numerous recent investigations concerning many different contact, limited-contact and non-contact sports. The presence of strength asymmetries in the lower-limbs of young athletes practicing various sporting disciplines is considered an intrinsic risk factor for injury; in such cases, compensation strategies should thus be implemented aimed at eliminating, or at least limiting, the degree of asymmetry in order to avoid the negative consequences asymmetries can have upon the health of young sportsmen and women on the long-term. The aim of the present study was to examine the presence of functional asymmetries in the lower-limbs of young tennis players in strength and speed drill performance and to test a specific balance-training programme in its capacity to effectively reduce such asymmetries. Twenty-three young tennis players were randomly assigned to the Experimental Group (EG) (n = 11: 4 females, 7 males; 13.2 ± 0.9 years; 50.8 ± 8.9 Kg; 1.63 ± 0.08 m) or Comparison Group (CG) (n = 12: 4 females, 8 males; 13.0 ± 0.9 years; 51.1 ± 9.2 Kg; 1.61 ± 0.09 m). To quantify percent asymmetries in lower-limb strength before (T0) and following (T1) training, performances were assessed in the one-leg hop test (OLH), side-hop test (SH) and side steps and forward 4.115-m test (4m-SSF). Performances in the 10 and 20m sprint tests and the Foran test were also assessed. The EG completed a total of 12 training sessions directed at balance training: two 30-minute sessions/week over a 6-week period. The CG followed an identical training schedule, but training sessions consisted of tennis-specific drills only. The results reveal significant differences between pre- and post-training tests in the EG only: the degree of lower-limb asymmetry was decreased in the EG following completion of the training programme, as assessed using the OLH test (p < 0.001), SH test (p < 0.001) and 4m-SSF test (p < 0.05). A significant interaction and main effect of training was also observed in the EG: balance training led to a significant reduction in the percent of asymmetry in lower-limb strength, as measured using the SH (p < 0.01), 4m-SSF (p < 0.01) and OLH (p < 0.05) tests. These results confirm that balance training exercises are able to counteract/reduce the degree of asymmetry in lower-limb strength in young tennis players.

Key points

• The determination of functional asymmetries in the lower-limbs has been the subject of numerous recent investigations aimed at the prevention of injuries in many different contact, limited-contact and non-contact sports.
• Sport-specific movements in tennis impose different loads upon the two lower-limbs and can cause the development of lower-limb strength asymmetries in young tennis players.
• The planning of athletic conditioning in young tennis players requires that strength in the lower-limbs is evaluated such that appropriate injury prevention strategies may be inserted into training programmes.
• Balance training exercises, and indeed all tasks performed on unstable surfaces, lead to benefits in sport-specific performance.

Key Words: Strength asymmetry, risk of injury, speed, lateral/side movements     

Similar Anti-Inflammatory Acute Responses from Moderate-Intensity Continuous and High-Intensity Intermittent Exercise

The purpose of this study was to compare the effect of high-intensity intermittent exercise (HIIE) versus volume matched steady state exercise (SSE) on inflammatory and metabolic responses. Eight physically active male subjects completed two experimental sessions, a 5-km run on a treadmill either continuously (70% vVO₂max) or intermittently (1:1 min at vVO₂max). Blood samples were collected at rest, immediately, 30 and 60 minutes after the exercise session. Blood was analyzed for glucose, non-ester fatty acid (NEFA), uric acid, lactate, cortisol, and cytokines (IL-6, IL-10 and TNF-α) levels. The lactate levels exhibited higher values immediately post-exercise than at rest (HIIE 1.34 ± 0.24 to 7.11 ± 2.85, and SSE 1.35 ± 0.14 to 4.06±1.60 mmol·L^-1, p < 0.05), but HIIE promoted higher values than SSE (p < 0.05); the NEFA levels were higher immediately post-exercise than at rest only in the SSE condition (0.71 ± 0.04 to 0.82±0.09 mEq/L, respectively, p < 0.05), yet, SSE promoted higher values than HIIE immediately after exercise (HIIE 0.72±0.03 vs SSE 0.82±0.09 mEq·L^-1, p < 0.05). Glucose and uric acid levels did not show changes under the different conditions (p > 0.05). Cortisol, IL-6, IL-10 and TNF-α levels showed time-dependent changes under the different conditions (p < 0.05), however, the area under the curve of TNF-α in the SSE were higher than HIIE (p < 0.05), and the area under the curve of IL-6 in the HIIE showed higher values than SSE (p < 0.05). In addition, both exercise conditions promote increased IL-10 levels and IL-10/TNF-α ratio (p < 0.05). In conclusion, our results demonstrated that both exercise protocols, when volume is matched, promote similar inflammatory responses, leading to an anti-inflammatory status; however, the metabolic responses are different.

Key points

• Metabolic contribution of both exercise, HIIE and SSE, was different.
• Both protocols leading to an anti-inflammatory status.
• HIIE induce a higher energy expenditure take into account total session duration.

Key words: High intensity intermittent exercise, steady state exercise, metabolism, inflammation, energy expenditure, cytokines     

Effects of Upper Body Eccentric versus Concentric Strength Training and Detraining on Maximal Force,Muscle Activation,Hypertrophy and Serum Hormones in Women

Effects of eccentric (ECC) versus concentric (CON) strength training of the upper body performed twice a week for 10 weeks followed by detraining for five weeks on maximal force, muscle activation, muscle mass and serum hormone concentrations were investigated in young women (n = 11 and n = 12). One-repetition bench press (1RM), maximal isometric force and surface electromyography (EMG) of triceps brachii (TB), anterior deltoid (AD) and pectoralis major (PM), cross-sectional area (CSA) of TB (Long (LoH) and Lateral Head (LaH)) and thickness of PM, as well as serum concentrations of free testosterone, cortisol, follicle-stimulating hormone, estradiol and sex hormone-binding globulin were measured. ECC and CON training led to increases of 17.2 ± 11.3% (p < 0.001) and 13.1 ± 5.7% (p < 0.001) in 1RM followed by decreases of -6.6 ± 3.6% (p < 0.01) and -8.0 ± 4.5% (p < 0.001) during detraining, respectively. Isometric force increased in ECC by 11.4 ± 9.6 % (p < 0.05) from week 5 to 10, while the change in CON by 3.9±6.8% was not significant and a between group difference was noted (p < 0.05). Maximal total integrated EMG of trained muscles increased only in the whole subject group (p < 0.05). CSA of TB (LoH) increased in ECC by 8.7 ± 8.0% (p < 0.001) and in CON by 3.4 ± 1.6% (p < 0.01) and differed between groups (p < 0.05), and CSA of TB (LaH) in ECC by 15.7 ± 8.0% (p < 0.001) and CON by 9.7 ± 6.6% (p < 0.001). PM thickness increased in ECC by 17.7 ± 10.9% (p < 0.001) and CON by 14.0 ± 5.9% (p < 0.001). Total muscle sum value (LoH + LaH + PM) increased in ECC by 12.4 ± 6.9% (p < 0.001) and in CON by 7.1 ± 2.9% (p < 0.001) differing between groups (p < 0.05) and decreased during detraining in ECC by -6.5 ± 4.3% (p < 0.001) and CON by -6.1 ± 2.8% (p < 0.001). The post detraining combined sum value of CSA and thickness was in ECC higher (p < 0.05) than at pre training. No changes were detected in serum hormone concentrations, but baseline free testosterone levels in the ECC and CON group combined correlated with changes in 1RM (r = 0.520, p < 0.016) during training. Large neuromuscular adaptations of the upper body occurred in women during ECC, and CON training in 10 weeks. Isometric force increased only in response to ECC, and total muscle sum value increased more during ECC than CON training. However, no changes occurred in serum hormones, but individual serum-free testosterone baseline concentrations correlated with changes in 1RM during strength training in the entire group. Both groups showed significant decreases in neuromuscular performance and muscle mass during detraining, while post detraining muscle sum value was only in ECC significantly higher than at pre training. Key points

• Maximal eccentric and concentric strength training in women for 10 weeks (only twice a week) led to great gains in dynamic strength of upper body.
• Upper body muscle mass increased more after eccentric than concentric strength training.
• During detraining for 5 weeks both groups showed decreases in strength and muscle mass.
• However, post-detraining combined sum muscle mass value was only in ECC higher than at pre-training.

Key words: Muscle force, training, EMG, mass, females, testosterone     

Sagittal Spinal Morphology in Highly Trained Adolescent Tennis Players

Sports with a predominance of forward-bending and extension postures have been associated with alterations in the sagittal spinal curvatures and greater risk of spinal injury. Because, the tennis players adopt these postures, the aims of this study were: 1) to describe spinal curvatures and pelvic tilt in male and female highly trained adolescent tennis players during relaxed standing posture and with thoracic spine corrected (in prone lying on the floor); and 2) to determine the frequency of thoracic hyperkyphosis and lumbar hypo/hyper lordosis in these postures. Forty adolescent tennis players (24 male and 16 female) aged 13-18 years, participated voluntarily in this study. The Spinal Mouse system was used to measure sagittal spinal curvatures and pelvic tilt. The mean values in the relaxed standing posture were 43.83° ± 7.87° (thoracic kyphosis), - 27.58° ± 7.01° (lumbar lordosis), and 13.38° ± 5.57° (pelvic tilt) for male tennis players, respectively; and 36.13° ± 6.69° (thoracic kyphosis), - 32.69° ± 5.06° (lumbar lordosis), 20.94° ± 5.36° (pelvic tilt) for female tennis players (p < 0.05 between genders in all spinal parameters). The male and female tennis players showed a frequency of 62.5% and 93.8% (p = 0.032) for neutral thoracic kyphosis, and 83.3% and 93.8% (p = 0.062) in neutral lumbar lordosis, respectively. In conclusion, due to the high percentage of neutral spinal curvatures in both male and female tennis players, to practice tennis in these levels does not alter sagittal spinal morphology in the relaxed standing posture in adolescent highly trained tennis players.

Key Points

• This study evaluated thoracic and lumbar spinal curvatures and pelvic tilt during several postures in young highly trained tennis players.
• Female tennis players showed statistically significant greater anterior pelvic tilt, lumbar lordosis and lower thoracic kyphosis than male tennis players.
• The high percentage of neutral thoracic kyphosis and lumbar lordosis posture in both groups of young tennis players in relaxed standing might affirm that tennis does not negatively affect sagittal spinal posture at these ages.
• A specific postural program could be recommended to improve the slumped sitting and maximal trunk flexion in knees extended postures.

Key words: Spinal mouse, posture, thoracic, lumbar, pelvic     

Hydration Status and Fluid Balance of Elite European Youth Soccer Players during Consecutive Training Sessions

The objective of the study was to investigate the hydration status and fluid balance of elite European youth soccer players during three consecutive training sessions. Fourteen males (age 16.9 ± 0.8 years, height 1.79 ± 0.06 m, body mass (BM) 70.6 ± 5.0 kg) had their hydration status assessed from first morning urine samples (baseline) and pre- and post-training using urine specific gravity (USG) measures, and their fluid balance calculated from pre- to post-training BM change, corrected for fluid intake and urine output. Most participants were hypohydrated upon waking (USG >1.020; 77% on days 1 and 3, and 62% on day 2). There was no significant difference between first morning and pre-training USG (p = 0.11) and no influence of training session (p = 0.34) or time (pre- vs. post-training; p = 0.16) on USG. Significant BM loss occurred in sessions 1-3 (0.69 ± 0.22, 0.42 ± 0.25, and 0.38 ± 0.30 kg respectively, p < 0.05). Mean fluid intake in sessions 1-3 was 425 ± 185, 355 ± 161, and 247 ± 157 ml, respectively (p < 0.05). Participants replaced on average 71.3 ± 64.1% (range 0-363.6%) of fluid losses across the three sessions. Body mass loss, fluid intake, and USG measures showed large inter-individual variation. Elite young European soccer players likely wake and present for training hypohydrated, when a USG threshold of 1.020 is applied. When training in a cool environment with ad libitum access to fluid, replacing ~71% of sweat losses results in minimal hypohydration (<1% BM). Consumption of fluid ad libitum throughout training appears to prevent excessive (≥2% BM) dehydration, as advised by current fluid intake guidelines. Current fluid intake guidelines appear applicable for elite European youth soccer players training in a cool environment.

Key Points

• The paper demonstrates a notable inter-participant variation in first morning, pre- and post-training hydration status and fluid balance of elite young European soccer players.
• On average, elite young European soccer players are hypohydrated upon waking and remain hypohydrated before and after training.
• Elite young European soccer players display varied fluid intake volumes during training, but on average do not consume sufficient fluid to offset fluid losses.
• Consecutive training sessions do not significantly impair hydration status, suggesting that elite young European soccer players consume sufficient fluid between training to maintain a stable hydration status and prevent excessive (≥2% body mass) dehydration
• Current fluid intake guidelines appear applicable to this population when training in a cool environment

Key words: Specific gravity, exercise, urine, adolescent     

Using Session RPE to Monitor Different Methods of Resistance Exercise

The purpose of this study was to compare session rating of perceived exertion for different resistance training techniques in the squat exercise. These techniques included traditional resistance training, super slow, and maximal power training. Fourteen college-age women (Mean ± SD; age = 22 ± 3 years; height = 1.68 ± 0. 07 m) completed three experimental trials in a randomized crossover design. The traditional resistance training protocol consisted of 6 sets of 6 repetitions of squats using 80% of 1-RM. The super slow protocol consisted of 6 sets of 6 repetitions using 55% of 1-RM. The maximal power protocol consisted of 6 sets of 6 repetitions using 30% of 1-RM. Rating of perceived exertion (RPE) measures were obtained following each set using Borg’s CR-10 scale. In addition, a session RPE value was obtained 30 minutes following each exercise session. When comparing average RPE and session RPE, no significant difference was found. However, power training had significantly lower (p < 0.05) average and session RPE (4.50 ± 1.9 and 4.5 ± 2.1) compared to both super slow training (7.81 ± 1.75 and 7.43 ± 1.73) and traditional training (7.33 ± 1.52 and 7.13 ± 1.73). The results indicate that session RPE values are not significantly different from the more traditional methods of measuring RPE during exercise bouts. It does appear that the resistance training mode that is used results in differences in perceived exertion that does not relate directly to the loading that is used. Using session RPE provides practitioners with the same information about perceived exertion as the traditional RPE measures. Taking a single measure following a training session would appear to be much easier than using multiple measures of RPE throughout a resistance training workout. However, practitioners should also be aware that the RPE does not directly relate to the relative intensity used and appears to be dependent on the mode of resistance exercise that is used.

Key Points

• The present study showed that session RPE values are not significantly different from the more traditional methods of measuring RPE during exercise bouts.
• Power training had significantly lower average and session RPE compared to both super slow training and traditional training
• It does appear that the resistance training mode that is used results in differences in perceived exertion that does not relate directly to the loading that is used.

Key words: Weight lifting, non-traditional resistance training     

Acute Effects of Static Stretching,Dynamic Exercises,and High Volume Upper Extremity Plyometric Activity on Tennis Serve Performance

The purpose of this study was to compare the acute effects of static stretching; dynamic exercises and high volume upper extremity plyometric activity on tennis serve performance. Twenty-six elite young tennis players (15.1 ± 4.2 years, 167.9 ± 5.8 cm and 61.6 ± 8.1 kg) performed 4 different warm-up (WU) routines in a random order on non-consecutive days. The WU methods consisted of traditional WU (jogging, rally and serve practice) (TRAD); traditional WU and static stretching (TRSS); traditional WU and dynamic exercise (TRDE); and traditional WU and high volume upper extremity plyometric activity (TRPLYP). Following each WU session, subjects were tested on a tennis serve ball speed test. TRAD, TRSS, TRDE and TRPLYO were compared by repeated measurement analyses of variance and post-hoc comparisons. In this study a 1 to 3 percent increase in tennis serve ball speed was recorded in TRDE and TRPLYO when compared to TRAD (p< 0.05). However, no significant change in ball speed performance between TRSS and TRAD. (p> 0.05). ICCs for ball speed showed strong reliability (0.82 to 0.93) for the ball speed measurements.The results of this study indicate that dynamic and high volume upper extremity plyometric WU activities are likely beneficial to serve speed of elite junior tennis players.

Key points

• After the traditional warm up in tennis, static stretching has no effect on serve speed.
• Tennis players should perform dynamic exercises and/or high volume upper extremity plyometric activities to improve their athletic performance.

Key words: velocity, warm-up, power, potentiation, ball speed     

Acute Differences in Foot Strike and Spatiotemporal Variables for Shod,Barefoot or Minimalist Male Runners

This study compared stride length, stride frequency, contact time, flight time and foot-strike patterns (FSP) when running barefoot, and in minimalist and conventional running shoes. Habitually shod male athletes (n = 14; age 25 ± 6 yr; competitive running experience 8 ± 3 yr) completed a randomised order of 6 by 4-min treadmill runs at velocities (V1 and V2) equivalent to 70 and 85% of best 5-km race time, in the three conditions. Synchronous recording of 3-D joint kinematics and ground reaction force data examined spatiotemporal variables and FSP. Most participants adopted a mid-foot strike pattern, regardless of condition. Heel-toe latency was less at V2 than V1 (-6 ± 20 vs. -1 ± 13 ms, p < 0.05), which indicated a velocity related shift towards a more FFS pattern. Stride duration and flight time, when shod and in minimalist footwear, were greater than barefoot (713 ± 48 and 701 ± 49 vs. 679 ± 56 ms, p < 0.001; and 502 ± 45 and 503 ± 41 vs. 488 ±4 9 ms, p < 0.05, respectively). Contact time was significantly longer when running shod than barefoot or in minimalist footwear (211±30 vs. 191 ± 29 ms and 198 ± 33 ms, p < 0.001). When running barefoot, stride frequency was significantly higher (p < 0.001) than in conventional and minimalist footwear (89 ± 7 vs. 85 ± 6 and 86 ± 6 strides·min^-1). In conclusion, differences in spatiotemporal variables occurred within a single running session, irrespective of barefoot running experience, and, without a detectable change in FSP.

Key points

• Differences in spatiotemporal variables occurred within a single running session, without a change in foot strike pattern.
• Stride duration and flight time were greater when shod and in minimalist footwear than when barefoot.
• Stride frequency when barefoot was higher than when shod or in minimalist footwear.
• Contact time when shod was longer than when barefoot or in minimalist footwear.
• Spatiotemporal variables when running in minimalist footwear more closely resemble shod than barefoot running.

Key Words: Flight time, contact time, foot-strike pattern     

Short Duration Heat Acclimation in Australian Football Players

This study examined if five sessions of short duration (27 min), high intensity, interval training (HIIT) in the heat over a nine day period would induce heat acclimation in Australian football (AF) players. Fourteen professional AF players were matched for VO₂peak (mL·kg^-1·min^-1) and randomly allocated into either a heat acclimation (Acc) (n = 7) or Control (Con) group (n = 7). The Acc completed five cycle ergometer HIIT sessions within a nine day period on a cycle ergometer in the heat (38.7 ± 0.5 °C; 34.4 ± 1.3 % RH), whereas Con trained in thermo-neutral conditions (22.3 ± 0.2 °C; 35.8 ± 0. % RH). Four days prior and two days post HIIT participants undertook a 30 min constant load cycling test at 60% V̇O₂peak in the heat (37.9 ± 0.1 °C; 28.5 ± 0.7 % RH) during which VO₂, blood lactate concentration ([Lac^-]), heart rate (HR), rating of perceived exertion (RPE), thermal comfort, core and skin temperatures were measured. Heat acclimation resulted in reduced RPE, thermal comfort and [Lac^-] (all p < 0.05) during the submaximal exercise test in the heat. Heart rate was lower (p = 0.007) after HIIT, in both groups. Heat acclimation did not influence any other measured variables. In conclusion, five short duration HIIT sessions in hot dry conditions induced limited heat acclimation responses in AF players during the in-season competition phase. In practice, the heat acclimation protocol can be implemented in a professional team environment; however the physiological adaptations resulting from such a protocol were limited.

Key points

• Some minor heat acclimation adaptations can be induced in professional AF players with five 27 min non-consecutive, short duration HIIT sessions in the heat.
• The heat acclimation protocol employed in this study was able to be implemented in a professional team sport environment during an actual competitive season.
• Elevating and maintaining a high core temperature sufficient for heat acclimation likely requires a longer heat training session or some pre-heating prior to exercise.

Key words: Core temperature, thermoregulation, high intensity interval training, adaptation, metabolism     

Nutrition for Tennis: Practical Recommendations

Tennis is a pan-global sport that is played year-round in both hemispheres. This places notable demands on the physical and psychological preparation of players and included in these demands are nutritional and fluid requirements both of training and match- play. Thus, the purpose of this article is to review nutritional recommendations for tennis. Notably, tennis players do not excel in any particular physiological or anthropometric characteristic but are well adapted in all areas which is probably a result of the varied nature of the training demands of tennis match play. Energy expenditures of 30.9 ± 5.5 and 45.3 ± 7.3 kJ·min^-1 have been reported in women and men players respectively regardless of court surface. Tennis players should follow a habitually high carbohydrate diet of between 6-10 g·kg^-1·d^-1 to ensure adequate glycogen stores, with women generally requiring slightly less than men. Protein intake guidelines for tennis players training at a high intensity and duration on a daily basis should be ~1.6 g·kg^-1·d^-1 and dietary fat intake should not exceed 2 g·kg^-1·d^-1. Caffeine in doses of 3 mg·kg^-1 provides ergogenic benefit when taken before and/or during tennis match play. Depending on environmental conditions, sweat rates of 0.5 to and over 5 L·hr^-1 and sodium losses of 0.5 - 1.8 g have been recorded in men and women players. 200 mL of fluid containing electrolytes should be consumed every change-over in mild to moderate temperatures of < 27°C but in temperatures greater than 27°C players should aim for ≤ 400 mL. 30-60 g·hr^-1 of carbohydrate should be ingested when match play exceeds 2 hours.

Key Points

• Tennis players should follow a habitually high carbohydrate diet of between 6-10 g·kg^-1 to ensure adequate glycogen stores, with women generally requiring slightly less than men. Protein intake guidelines for tennis players training at a high intensity and duration on a daily basis should be ~1.6 g·kg^-1·d^-1. Dietary fat intake should not exceed 2 g·kg^-1·d^-1.
• Caffeine in doses of 3 mg·kg^-1 can provide ergogenic benefit when taken before and/or during tennis match play.
• 200 mL of fluid containing electrolytes should be consumed every change-over in mild to moderate temperatures of < 27°C but in temperatures greater than 27°C players should aim for ≥ 400 mL.
• 30-60 g·hr^-1 of carbohydrate should be ingested when match play exceeds 2 hours.
• During periods of travel, specific dietary requirements can be communicated with agencies and hotels prior to arrival and in the event that suitably nutritious foods are not available in the host country, players can bring or send non-perishable foods and goods where customs and quarantine laws allow.

Key words: Caffeine, diet, electrolyte, supplements, carbohydrate, fluid     

A Mixed-Method Approach of Pre-Cooling Enhances High-Intensity Running Performance in the Heat

We investigated whether single or combined methods of pre-cooling could affect high-intensity exercise performance in a hot environment. Seven male athletes were subjected to four experimental conditions for 30 min in a randomised order. The four experimental conditions were: 1) wearing a vest cooled to a temperature of 4 ℃ (Vest), 2) consuming a beverage cooled to a temperature of 4 ℃ (Beverage), 3) simultaneous usage of vest and consumption of beverage (Mix), and 4) the control trial without pre-cooling (CON). Following those experimental conditions, they exercised at a speed of 80% VO₂max until exhaustion in the heat (38.1 ± 0.6 ℃, 55.3 ± 0.3% RH). Heart rate (HR), rectal temperature (T_core), skin temperature (T_skin), sweat loss (SL), urine specific gravity (USG), levels of sodium (Na⁺) and potassium (K⁺), rating of perceived exertion (RPE), thermal sensation (TS), and levels of blood lactic acid ([Bla]) were monitored. Performance was improved using the mixed pre-cooling strategy (648.43 ± 77.53 s, p = 0.016) compared to CON (509.14 ± 54.57 s). T_core after pre-cooling was not different (Mix: 37.01 ± 0.27 ℃, Vest: 37.19 ± 0.33 ℃, Beverage: 37.03 ± 0.35 ℃) in all cooling conditions compared to those of CON (37.31 ±0.29 ℃). A similar T_core values was achieved at exhaustion in all trials (from 38.10 ℃ to 39.00 ℃). No difference in the level of USG was observed between the conditions. Our findings suggest that pre-cooling with a combination of cold vest usage and cold fluid intake can improve performance in the heat.Key points

• Precooling strategies with 30 min independent or simultaneous precooling maneuvers could improve running performance of 80% VO₂max in hot and humid climatic conditions compared with the control condition.
• Wearing a 4℃ vest might augment the capacity of heat dissipation by decreasing T_skin.
• Ingesting a 4℃ beverage might increase the capacity of heat storage and maintain homeostasis by reducing T_core, HR and [Bla].
• The mix method-precooling maneuver seems to be more effective than others by maintaining core-to-skin thermal gradient and fortifying heat storage to relieve thermophysiological strain.

Key words: Cooling prior to exercise, external and internal cooling, hyperthermia, thermoregulation, high-intensity aerobic exercise     

The Effects of Pre- and Post-Exercise Whey vs. Casein Protein Consumption on Body Composition and Performance Measures in Collegiate Female Athletes

Two of the most popular forms of protein on the market are whey and casein. Both proteins are derived from milk but each protein differs in absorption rate and bioavailability, thus it is possible that each type of protein may contribute differently to the adaptations elicited through resistance training. Therefore, the purpose of this study was to investigate the potential effects of ingestion of two types of protein in conjunction with a controlled resistance training program in collegiate female basketball players. Sixteen NCAA Division III female basketball players were matched according to body mass and randomly assigned in a double-blind manner to consume 24 g whey protein (WP) (N = 8, 20.0 ± 1.9 years, 1.58 ± 0.27 m, 66. 0 ± 4.9 kg, 27.0 ± 4.9 %BF) or 24 g casein protein (CP) (N = 8, 21.0 ± 2.8 years, 1.53 ± 0.29 m, 68.0 ± 2.9 kg, 25.0 ± 5.7 %BF) immediately pre- and post-exercise for eight weeks. Subjects participated in a supervised 4-day per week undulating periodized training program. At 0 and 8 weeks, subjects underwent DXA body composition analysis, and at 0 and 8 weeks underwent one repetition maximum (1RM) strength, muscle endurance, vertical jump, 5-10-5 agility run, and broad jump testing sessions. Data were analyzed using repeated measures ANOVA, and presented as mean ± SD changes from baseline after 60 days. No significant group x time interaction effects were observed among groups in changes in any variable (p > 0.05). A significant time effect was observed for body fat (WP: -2.0 ± 1.1 %BF; CP: -1.0 ± 1.6 %BF, p < 0.001), lean mass (WP: 1.5 ± 1.0 kg; CP: 1. 4 ± 1.0 kg, p < 0.001), fat mass (WP: -1.3 ± 1.2 kg; CP: -0.6 ± 1.4 kg, p < 0.001), leg press 1RM (WP: 88.7 ± 43.9 kg; CP: 90.0 ± 48.5 kg, p < 0.001), bench press 1RM (WP: 7.5 ± 4.6 kg; CP: 4.3 ± 4.5 kg, p = 0.01), vertical jump (WP: 4.1 ± 1.8 cm; CP: 3.5 ± 7.6 cm, p < 0.001), 5-10-5 (WP: -0.3 ± 0.2 sec; CP: -0.09 ± 0.42 sec, p < 0.001), and broad jump (WP: 10.4 ± 6.6 cm; CP: 12. 9 ± 7.1 cm, p < 0.001). The combination of a controlled undulating resistance training program with pre- and post-exercise protein supplementation is capable of inducing significant changes in performance and body composition. There does not appear to be a difference in the performance- enhancing effects between whey and casein proteins.

Key points

• Females can experience and increase in performance makers from consuming protein after resistance training.
• Females can have a decreased body fat composition when ingesting protein with daily resistance training and conditioning.
• There was no significant difference in performance markers between whey and casein.

Key words: whey, casein, protein, females, body composition, performance     

Does the Timing of Measurement Alter Session-RPE in Boxers?

The purpose of this study was to compare the influence of measuring the overall session rating of perceived exertion (session-RPE) at 10 vs. 30 minutes following exercise. Eight boxers completed three different standardized training sessions of different intensities (easy, moderate and hard) in a matchedpairs, randomized research design. Exercise intensity was assessed during each bout by measuring heart rate, blood lactate concentration and session-RPE. To assess the effect of measurement timing on session-RPE, RPE data were collected either 10 or 30 minutes post-exercise. There was no significant effect of measurement time on session-RPE values following easy (10 minutes: session-RPE = 1.3 ± 1.0 Arbitrary Unit (AU), %Heart Rate Reserve (HRR) = 49.5 ± 11.1, and ∆Blood lactate = -2.3 ± 16.3%; 30 minutes: session-RPE = 1.7 ± 1.0 AU, %HRR = 51.3 ± 10.8, and ∆Blood lactate = 0.7 ± 25.2%), moderate (10 minutes: session-RPE = 2.7 ± 1.6 AU, %HRR = 67.2 ± 10.8, and ∆Blood lactate = 2.2 ± 19%; 30 minutes: session-RPE = 2.5 ± 0.9 AU, %HRR = 67.2 ± 5.9, and ∆Blood lactate = 24.5 ± 17.1%) and hard (10 minutes: session-RPE = 5.7 ± 1.0 AU, %HRR = 88.1 ± 6.3, and ∆Blood lactate = 146.3 ± 87.9%; 30 minutes: session-RPE = 5.8 ± 1.9 AU, %HRR> = 83.3 ± 8.0, and ∆Blood lactate = 91.6 ± 39%) sessions. In conclusion, our findings suggest that session-RPE can be used in boxing training routines across a range of intensities and accurate measurements can be determined as early as 10 minutes after exercise.

Key Points

• It is difficult to quantify and monitoring the external training load in martial arts (e.g. Aikido, Kung Fu, Judo) and physical combat sports (e.g. Boxing, Muay Thai), session RPE method appears to be a reliable method to quantifying training load in those sports.
• For many athletes it is impractical to wait 30 minutes after training session to provide a session-RPE. The present findings show that collecting ses-sion-RPE measures at 10 min following exercise ses-sions of various intensities (i.e. easy, moderate, and hard) provide similar values as if taken 30 min fol-lowing the session.
• Our data have significant practical benefit and fur-ther support the practical usefulness of session-RPE for measuring internal training load in sport.

Key Words: boxing, perceived exertion, internal load, lactate, combat sports, exercise intensities     

A Combination of Ice Ingestion and Head Cooling Enhances Cognitive Performance during Endurance Exercise in the Heat

This study assessed the effectiveness of head cooling during exercise in the heat on cognitive performance, either alone or with ice ingestion. Ten healthy males, non-acclimatized to heat, ran (70% V̇O₂peak) for 2×30 min in heat (35 ± 0.9°C, 68.2 ± 6.9% RH). Participants completed 3 trials: 10 min of head cooling during exercise (HC); precooling with crushed ice (7gikg^-1) and head cooling during exercise (MIX); or no-cooling/control (CON). Working memory was assessed using the automated operation span task (OSPAN) and serial seven test (S7). Following MIX, S7 scores were improved compared to CON (12 ± 9.5, p = 0.004, d = 1.42, 0.34-2.28) and HC (4 ± 5.5, p = 0.048, d = 0.45, -0.47 to 1.3) during exercise. Moderate to large effect sizes were recorded for S7 and OSPAN following MIX and HC compared to CON, suggesting a tendency for improved cognitive performance during exercise in heat. Following precooling (MIX), core body temperature (T_c) and forehead temperature (T_h) were lower compared to baseline (-0.75 ± 0.37°C, p < 0.001; -0.31 ± 0.29°C, p = 0.008, respectively) but not in HC or CON (p > 0.05). Thermal sensation (TS) was lower in MIX and HC compared to CON during exercise (p < 0.05). The reduction in T_c, T_h and TS with MIX may have attenuated the effect of heat and subsequently improved working memory during exercise in heat. Key points

• The combination of crushed ice ingestion (precooling) and head cooling cap (percooling) significantly improved cognitive performance (working memory) on endurance exercise in the heat and this effect is attributed to the reduction in reduced core temperature, forehead temperature and thermal sensation.
• Single cooling method during exercise via head cooling cap effective for attenuating impairment of working memory by providing maintenance during endurance exercise in the heat and this associated with reduced forehead temperature and thermal sensation following cooling.
• Decrement in forehead temperature and thermal sensation with head cooling during exercise may benefit cognitive performance although with the absence of core body temperature.

Key words: Cooling, forehead temperature, cognitive function     

The Relationships Between Simulated Tennis Performance and Biomarkers for Nitric Oxide Synthesis

Tennis performance requires a good aerobic endurance and recovering capacity. Nitric oxide (NO) is a gas which is not only a vasodilator and antioxidant but it also regulates the use of oxygen and glucose. The aim of this study was to examine the relationships between simulated tennis performance test (PT) and NOx (sum of nitrate+nitrite) levels and lactate elimination speed (LES). Twenty well trained male tennis players with game levels of ITN 4 (International Tennis Number) and lower (mean ± SD; age 22.9 ± 2.6 yrs; height 1.82 ± 0.06 m and mass 75.7 ± 8.0 kg) participated in the study. Participants performed three 4-min bouts and a 2-min continuous groundstroke against balls projected from a tennis ball machine at speeds of 50, 55, 62 and 70 km·h^-1. After this exercise, subjects were given a 20 min passive rest. After each period and at during the recovery phase; plasma NOx, glucose (GLU) and lactate (LA) levels were determined. LES was calculated during passive recovery. GLU, LA and heart rate (HR) showed a linear increase in comparison to the values in the previous step while PT decreased significantly. Following each period NOx and glucose levels increased independently, but their decreasing rates in recovery phase were related (r = 0.470, p < 0.05). The successive increase in NOx and GLU parameters between the third and the forth periods was significant (p < 0.05). Only in the third period was there a significant relation between PT and NOx (r = 0.494; p < 0.05). In the present study, no significant relationship was found between PT and GLU, LA levels and LES. No significant correlation was found between simulated tennis performance and blood NOx levels. However the addition of loads like those in the third period in tennis trainings can be beneficial for performance in trained tennis players. It is recommended that the relationships between tennis performance with NOx and GLU are studied during a real tennis match.

Key Points

• In a sport like tennis which lasts 2-6 hours and has short rests, performance depends on the player’s capacity to perform the intensive exercise intermittently. Therefore, recovering potential is important in tennis.
• In none of the periods of this study were the expected (significant) relations observed of the athletes. Therefore, it can be claimed that LA increase, LA elimination and aerobic endurance do not play a significant role in the performance and the decrease in performance in this exercise model.

Key words: Blood lactate, heart rate, nitric oxide, stroke performance, tennis     

Heavy Resistance Training and Supplementation With the Alleged Testosterone Booster Nmda has No Effect on Body Composition,Muscle Performance,and Serum Hormones Associated With the Hypothalamo-Pituitary-Gonadal Axis in Resistance-Trained Males

The effects of 28 days of heavy resistance training while ingesting the alleged testosterone-boosting supplement, NMDA, were determined on body composition, muscle strength, serum cortisol, prolactin, and hormones associated with the hypothalamo-pituitary- gonadal (HPG) axis. Twenty resistance-trained males engaged in 28 days of resistance training 4 times/wk while orally ingesting daily either 1.78 g of placebo (PLAC) or NMDA. Data were analyzed with separate 2 x 2 ANOVA (p < 0.05). Criterion measures involved body composition, muscle strength, serum cortisol, prolactin, and gonadal hormone levels [free and total testosterone, luteininzing hormome (LH), gonadotrophin releasing hormone (GnRH), estradiol], and were assessed before (Day 0) and after (Day 29) resistance training and supplementation. No changes were noted for total body water and fat mass in response to resistance training (p > 0.05) or supplementation (p > 0.05). In regard to total body mass and fat-free mass, however, each was significantly increased in both groups in response to resistance training (p < 0.05), but were not affected by supplementation (p > 0.05). In both groups, lower-body muscle strength was significantly increased in response to resistance training (p < 0.05); however, supplementation had no effect (p > 0.05). All serum hormones (total and free testosterone, LH, GnRH, estradiol, cortisol, prolactin) were unaffected by resistance training (p > 0.05) or supplementation (p > 0.05). The gonadal hormones and cortisol and prolactin were unaffected by 28 days of NMDA supplementation and not associated with the observed increases in muscle strength and mass. At the dose provided, NMDA had no effect on HPG axis activity or ergogenic effects in skeletal muscle.

Key Points

• In response to 28 days of heavy resistance training and NMDA supplementation, similar increases in muscle mass and strength in both groups occurred; however, the increases were not different between supplement groups.
• The supplementation of NMDA had no preferential effect on augmenting testosterone or decreasing estrogen, cortisol, and prolactin.
• While resistance training was effective in increasing muscle mass and strength, it was not preferentially due to NMDA supplementation.
• At the dose provided, NMDA supplementation for 28 days combined with resistance training does not increases muscle mass and strength due to its ability to elevate endogenous testosterone levels and lower cortisol and prolactin when compared to placebo.

Key Words: D-Aspartic Acid, N-Methyl-D-Aspartic Acid, testosterone, resistance training     

Effect of Different Rest Intervals,Between Sets,on Muscle Performance During Leg Press Exercise,in Trained Older Women

The purpose of this study was to assess the effect of different rest intervals (RI) between sets on number of repetitions, sustainability of repetitions, and total volume during a leg press exercise. Seventeen resistance-trained older women (68.0 ± 5.9 years, 71. 2 ± 11.7 kg, 1.58 ± 0.07 m) participated in the study. All participants performed three sets to voluntary exhaustion, with loads that corresponded to 15 maximum repetitions, in two experimental sessions (that ranged from 48 to 72 hours apart). In each session, one of two RI (one-minute: RI-1 and three minute: RI-3) was tested, employing a randomized and counterbalanced design. For both RI, significant reductions (p < 0.05) were observed in the number of repetitions and sustainability of repetitions, from the first to the second and third sets. Differences (p < 0.05) between the RI also were observed in the two final sets. The total volume for the RI-3 session was statistically higher (29.4%, p < 0.05) as compared to the RI-1 session. The length of the RI between sets influenced the number of repetitions, sustainability of repetitions, and total volume. The longer RI should be used, therefore, when the goal of training is to increase the total volume.

Key points

• This study examined the influence of rest intervals, between sets, on muscle performance during leg press exercise, in trained older women.
• When multiple sets were performed to voluntary exhaustion, neither short and long rest interval (1 and 3 minutes, respectively) promoted the sustainability of repetitions in subsequent sets.
• A longer rest interval seems to be necessary for a higher number of repetitions in subsequent sets, and with increase in time of tension and total volume.

Key words: Aging, muscle fatigue, muscle endurance, recovery.     

Effects of Between-Set Interventions on Neuromuscular Function During Isokinetic Maximal Concentric Contractions of the Knee Extensors

The presents study investigated the effects of between-set interventions on neuromuscular function of the knee extensors during six sets of 10 isokinetic (120°·s^-1) maximal concentric contractions separated by three minutes. Twelve healthy men (age: 23.9 ± 2.4 yrs) were tested for four different between-set recovery conditions applied during two minutes: passive recovery, active recovery (cycling), electromyostimulation and stretching, in a randomized, crossover design. Before, during and at the end of the isokinetic session, torque and thigh muscles electromyographic activity were measured during maximal voluntary contractions and electrically-evoked doublets. Activation level was calculated using the twitch interpolation technique. While quadriceps electromyographic activity and activation level were significantly decreased at the end of the isokinetic session (-5.5 ± 14.2 % and -2.7 ± 4.8 %; p < 0.05), significant decreases in maximal voluntary contractions and doublets were observed after the third set (respectively -0.8 ± 12.1% and -5.9 ± 9.9%; p < 0.05). Whatever the recovery modality applied, torque was back to initial values after each recovery period. The present results showed that fatigue appeared progressively during the isokinetic session with peripheral alterations occurring first followed by central ones. Recovery interventions between sets did not modify fatigue time course as compared with passive recovery. It appears that the interval between sets (3 min) was long enough to provide recovery regardless of the interventions.

Key points

• Allowing three minutes of recovery between sets of 10 maximal concentric contractions would help the subjects to recover from the peripheral fatigue induced by each set and therefore to start each new set with a high intensity.
• During this type of session, with three minutes between sets, passive recovery is sufficient; there is no need to apply complicated recovery interventions.

Key words: Electromyography, electromyostimulation, stretching, recovery, maximal strength