Estimated aerobic power, muscular strength and flexibility in elite Brazilian Jiu-Jitsu athletes

Objective

This study was designed to estimate the maximum oxygen uptake, muscular strength and flexibility of elite Brazilian Jiu-Jitsu athletes.

Methods

The sample consisted of eleven Brazilian Jiu-Jitsu athletes (25.8 ± 3.3 years old) who were medallists at national and/or international competitions. The aerobic power was estimated by a treadmill test, according to the Bruce Protocol. The maximal isometric strength (hand, leg and back) was measured by specific dynamometric tests. We used sit-ups and push-ups to evaluate abdominal and upper limb strength endurance, respectively. We applied the sit-and-reach test to determine hip, back and posterior flexibility of the muscles of the lower limbs.

Results

We observed a VO_2max of 49.4 ± 3.6 mL/kg per minute for the treadmill test. We observed measures of 43.7 ± 4.8 kgf for the right maximal isometric handgrip strength, 40.1 ± 3.8 kgf for the left maximal isometric handgrip strength, 185.5 ± 36.0 kgf for the maximal isometric back strength and 154.3 ± 41.9 kgf for the maximal isometric leg strength. In the strength endurance test, the athletes performed 52 ± 7 repetitions in a 1-min sit-up test, and 40 ± 8 repetitions in the push-up test. In the sit-and-reach test, the athletes had an average score of 36 ± 9 cm.

Conclusions

The elite Brazilian Jiu-Jitsu athletes had medium aerobic power and flexibility, excellent abdominal and upper body strength endurance and maximal isometric back strength. However, these athletes did not have high maximal isometric handgrip or leg strength.     

Match activity and physiological responses during a junior female singles tennis tournament

Objective

To assess physiological load in conjunction with individual patterns of match‐play activity in junior female tennis players during actual singles tennis competition.

Methods

Eight elite junior female tennis players (n = 8; mean (SD) age, 17.3 (1.9) years) took part in a 2 day invitational tournament. Activity pattern analysis was performed during competitive matches. Heart rate and blood lactate concentrations were measured during selected changeovers breaks in play.

Results

The activity profile of junior female players were: rally duration, (mean (SD)) 8.2 (5.2) s; rest time between rallies, 17.7 (6.5) s; effective playing time, 21.9 (3.8)%; strokes per rally, 2.7 (1.7); changes of direction per rally, 2.3 (1.4). The mean (SD) heart rate and blood lactate concentration recorded during the matches were 161 (5) beats/min and 2.0 (0.8) mmol/litre. Heart rate and blood lactate concentration values were influenced by the characteristics of the match and mean (SD) heart rate was significantly higher (p = 0.004) during service games (166 (15.4) beats/min) than in return games (156 (19.6) beats/min), while blood lactate concentrations were not significantly different (p = 0.83) between service (2.3 (0.6) mmol/litre) and return games (2.3 (0.9) mmol/litre). We found a significant (p<0.05) positive relationship between rally duration, strokes per rally, changes of direction and blood lactate and heart rate responses, with stronger correlations when the players were serving.

Conclusions

The physiological (ie, blood lactate and heart rate) responses associated with match play were influenced by the characteristics of the match (rally duration, strokes per rally and changes of direction), with higher heart rate on service position. Training programs should reflect these demands placed on female players during competitive match play.The physical aspects related to singles tennis performance have been quite well studied in male participants.^1,2,3,4,5,6 Tennis match play is characterised by short bouts of intermittent exercise interrupted by several periods of longer duration and lower intensity.⁷ Matches vary substantially in duration, often lasting more than an hour and in some cases more than 5 h.^4,7,8,9 Most matches consist of work and rest periods of 5–10 s and 10–20 s, respectively, interspersed with longer rest periods (ie, 90 s between changeover breaks).⁷ During each point, players typically hit the ball an average of 2–3 times and make four directional changes per rally.^10,11 Match activity, however, can be influenced by factors such as court surface, ball type and sex.^12,13 In this regard, O''Donoghue and Ingram¹² have reported that rallies analysed in Grand Slam women''s singles matches were significantly longer (7.1 s/rally) than those in men''s singles matches (5.2 s/rally), together with a greater proportion of baseline rallies in women''s singles. In addition, women played significantly less strokes/s, hit fewer aces, won fewer service games and committed more double faults. Although this study provides information about differences in activity patterns between men''s and women''s singles, to date, no previous study has documented the activity patterns of elite female junior tennis players.The physical aspects of the game have been reported to influence acute physiological responses during on‐court practice.^6,7 For example, Mendez‐Villanueva et al⁶ have found that activity patterns (eg, rally duration) can influence the physiological demands in men''s singles tennis, with higher blood lactate concentrations in matches with longer rallies and a higher number of strokes per rally. Thus, as activity profile during men''s and women''s singles tennis has been reported to be significantly different,¹² the associated physiological responses might also differ. However, to the best of our knowledge, the physiological load during competitive tennis in junior female players has never been investigated. Consequently, the purpose of the present study was to investigate the patterns of physical activity and the physiological load associated with elite junior female singles tennis during an invitational tennis tournament.     

Specific incremental field test for aerobic fitness in tennis

Objectives

To compare metabolic and cardiorespiratory responses between subjects undergoing incremental treadmill (non‐specific) and tennis field based (sport specific) tests.

Methods

Nine junior competitive tennis players randomly performed two incremental protocols to exhaustion: a treadmill test (TT) and a tennis specific fitness test (FT). The FT consisted of repeated displacements replicating the game of tennis at increasing speed on a court. In both tests, ventilatory variables and heart rate (HR) were determined at the ventilatory threshold (VT), respiratory compensation point (RCP), and maximal loads (max). Blood lactate concentration was determined at the point of volitional fatigue.

Results

Percentage (mean (SD)) maximal HR (83.6 (5.1) v 83.0 (2.8) and 92.1 (2.1) v 92.3 (2.1)%, respectively) and percentage maximal oxygen uptake (VO_2max) (69.4 (8.1) v 73.5 (6.1) and 84.4 (6.5) v 85.5 (8.7)%, respectively) at the VT and RCP were not different between the FT and TT subjects, whereas VO_2max was higher in the FT than in the TT (63.8 (3.0) v 58.9 (5.3) ml/min/kg; p<0.05). Blood lactate concentration (10.7 (3.0) v 10.6 (4.3) mmol/l) did not differ between the TT and FT.

Conclusions

Although cardiorespiratory variables were not different at submaximal intensities between the two tests, VO_2max values derived from laboratory measurements were underestimated. Using field testing in addition to treadmill testing provides a better measurement of a player''s individual fitness level and may be routinely used to accurately prescribe appropriate aerobic exercise training.     

A comparative analysis between head-out underwater walking and land-based treadmill walking in a group of healthy asymptomatic elderly

Purpose

This study aimed to compare the cardiometabolic responses (VO₂ and HR) and rate of perceived exertion (RPE) of walking, at the same percentage of heart rate reserve (HR_res) plus resting heart rate (HR_rest), on a nonmotorized aquatic treadmill and on a land-based motorized treadmill, in healthy older adults.

Methods

Eighteen healthy older adults, all men, were required to perform two trials in random order, one on an underwater nonmotorized treadmill and the other on land motorized treadmill. Each trial consisted in a 20-min walk. The first 10 min carried out at 40% of HR_res + HR_rest, and the second 10 min at 60% of HR_res + HR_rest. The HR_res and HR_rest percentages were calculated on the basis of a maximal treadmill test on land.

Results

HR, VO₂, VE, and RPE outcomes were significantly different between the two executive frequencies, but not between the two environment conditions. The results indicate that cardiometabolic responses and rate of perceived exertion are similar during a walk on a land motorized treadmill and on a nonmotorized aquatic treadmill, at the same percentage of heart rate reserve.

Conclusions

The present investigation indicates that data of land maximal exercise test can be used to prescribe water aerobic exercise.

     

Stress reaction of the humerus in tennis players

Background

Overuse injuries are a frequent occurrence among competitive athletes. When analysing the incidence of overuse injuries in tennis players, it has been determined that a significant number of these injures occur in the upper limb area. In this study, we describe five cases of a stress‐induced injury to the middle and distal humerus occurring mainly due to repetitive serving.

Methods

Athletes studied were competitive tennis players and elite junior players, two of whom played at international level. Four of the five were male. In all cases, diagnosis was confirmed by magnetic resonance imaging examination. The treatment of middle and distal humeral stress reactions consisted of physical therapy, which focused on analgesia and muscle strengthening. In addition, we analysed each tennis player''s strokes in order to identify modifications that would decrease the amount of stress that the upper limbs were subjected to during the service motion.

Results

The players in our study missed on average 3 weeks of play and at follow‐up after 1 year were able to play symptom free.

Conclusions

Our study highlights the need for coaches, physicians and players to be aware of distal humeral pain and understand treatment options in order to prevent further injury, including stress fractures.The motions associated with certain tennis strokes have been shown to place the upper limbs of competitive and professional tennis players at risk of injury. Recently published studies have reported chronic injuries in this region.^1,2,3,4 As a consequence of these injuries, the athlete is required to spend weeks or even months recovering and is unable to participate in on‐court activities. Muscle and tendon overuse injuries have been well documented in tennis players.² However, only a limited number of studies have focused on bone stress injuries associated with overuse.^3,4,5 Furthermore, most of the studies examining tennis‐related bone stress injuries concentrate on injuries to the trunk and lower limbs.^5,6 In fact, only three articles were retrieved that reported stress reactions involving the humerus in tennis players.^3,4,7It has been well documented that the elbow, as well as the middle and distal humerus, are prone to overuse injuries.^4,7 Injuries to this portion of the arm occur primarily during the acceleration phase of the service motion, when the arm moves into internal rotation.⁸ Valgus stress of the elbow also is a common occurrence during this motion.⁸ The repetition of strokes during practice and matches can lead to symptoms of pain and weakness in that region that if left untreated can progress from a bone stress reaction to a complete stress fracture.This study examined five cases in which overuse resulted in an injury to the middle and distal humerus of competitive tennis players. Our objective was to illustrate the importance of this differential diagnosis to prevent stress fractures in competitive tennis players.     

Effets d'une restriction hydrique et alimentaire prolongée (ramadan) sur la performance et les réponses cardiovasculaires au cours d'un exercice incrémental en milieu tropical chaud

Backgroung

Previous studies showed that maximal oxygen uptake and maximal heart rate were not different during prolonged fasting (ramadan) compared to normal feeding period. However, the effect of ramadan on the blood pressure response during incremental exercise has not been investigated.

Objective

This study aimed to evaluate the evolution of blood pressure during incremental trial in ramadan period.

Methods

Twelve young trained male aged 24 ± 4 yrs participated as voluntary subjects. Their anthropometric parameters, maximal aerobic power and maximal heart were measured in fasting and in normal feeding periods during incremental trial on cycle ergometer.

Results

No significant difference was observed in any anthropometric parameter. Maximal aerobic power of fasting period was significantly less (P < 0,05) compared to normal feeding. Heart rate at rest, at maximal exercise and during a 15 min period of recovery was not significantly affected. Systolic blood pressure of fasting period at maximal power was significantly lower than during the control period (P < 0,05).

Conclusion

Ramadan negatively influences the capacity of maximal power and cardiovascular response at maximal power.     

Air temperature and physiological and subjective responses during competitive singles tennis

Objectives

This report describes the thermal stresses and strains during competitive singles tennis.

Methods

Thermoregulatory responses were investigated during best of three set tennis matches among 25 players. A total of 86 observations were made from 43 matches played, covering each season, with ambient temperatures ranging from 14.5 to 38.4°C. Core body temperature and skin temperature were recorded each minute throughout the match, whilst heart rate was logged every 15 s. Body mass and fluid intake were measured before the match, after 30 min of play and at the completion of the match to determine sweat rate. Subjective ratings of thermal strain included thermal comfort, sweatiness and perceived exertion. The thermal environment was assessed by dry bulb, wet bulb and natural wet bulb temperatures, globe temperature and wind speed.

Results

Mean (SD) core temperature after 30 min of play was 38.4°C (0.4°C), and demonstrated no association with air temperature or wet bulb globe temperature. Mean skin temperature was 31.8°C (2.3°C) ranging from 25.7 to 36.5°C, and showed a positive association with air temperature (p<0.001). Heart rate varied widely during play, resulting in a mean (SD) response of 136.1 (13.7) beats/min and no association with air temperature. Sweat rate averaged 1.0 (0.4) litres/h (0.2–2.4 litres/h) or 12.8 (5.5) ml/kg/h (2.7–26.0 ml/kg/h), and demonstrated a positive relationship with air temperature (p<0.001). All subjective responses showed positive correlations with air temperature (p<0.001).

Conclusions

Stressful environmental conditions produce a high skin temperature and rating of thermal discomfort. However, overall thermoregulatory strain during tennis is moderate, with core temperature remaining within safe levels.Tennis is played by people of all ages and standards around the world in a wide range of climates. Despite this, the thermoregulatory stresses and strains experienced by tennis players are poorly understood.All tennis players, whether professional or amateur, would benefit from a greater understanding of the environmental stresses and thermoregulatory strains associated with playing tennis. Individuals and organisations with a duty of care towards players also require objective information on which to base recommendations and policies for managing heat stress in training and competition.Thermal stress is the combination of six factors that combine to burden the thermoregulatory system in the effort to maintain core body temperature within tolerable limits.¹ The six factors comprising heat stress are: (1) metabolic heat production, (2) air temperature, (3) absolute humidity, (4) radiant temperature, (5) air movement, and (6) clothing.¹ Thermal strain refers to the thermoregulatory and subjective responses to a thermal stress. Thermoregulatory strains include core body temperature, skin temperature, sweat rate, and heart rate, whilst subjective strains include thermal sensation and perceived exertion.¹ Empirical observations of thermal stress and the corresponding thermoregulatory strains during tennis play are required to determine whether players are at risk of heat illness, and similarly to determine whether they are able to maintain thermal comfort.No previously published studies have made a thorough assessment of the thermal environment and players'' corresponding thermoregulatory responses during tennis. Heart rate, oxygen consumption, core body temperature, skin temperature, and sweat rate have been measured during tennis in a number of studies.^{2,3,4,5,6,7,8,9,10} However, in general these studies have not described the demands of tennis in competition in a wide range of environmental conditions and have not represented the wider tennis community. Only one known study included both genders,⁶ and one other study was the only one to make observations during a best of three sets singles match¹² rather than a time‐restricted match. All of these studies used a relatively small sample of subjects and often only one match was played per subject. A number of the observations in these studies caused disruption to normal player behaviour and performance, and/or the rules of tennis. For example, observations were often measured at various intervals during play, which might not be representative of the activity periods of a real match. The heart rate response in tennis demonstrates a wide variation, therefore continuous recording throughout the match at frequent intervals would be more accurate. It was also be advantageous to continuously record core body temperature throughout the match in order to determine: (1) whether thermal equilibrium is achieved and core temperature is controlled or rises continuously, and (2) the change in core temperature. A single measurement at the end of the match would not provide such information. Furthermore, air temperature and relative humidity were the only environmental stresses measured, not providing a complete assessment of the thermal stress.This paper reports the thermoregulatory and subjective responses to singles tennis in a wide range of thermal environments. This information is required as the basis for developing predictive models for assessing heat stress in tennis.     

Feasibility and safety of exercise stress testing using an anti-gravity treadmill with Tc-99m tetrofosmin single-photon emission computed tomography (SPECT) myocardial perfusion imaging: A pilot non-randomized controlled study

Background

Exercise is the AHA/ACC guideline-recommended stress modality for myocardial perfusion imaging, but many patients are unable to exercise to target heart rate on a conventional treadmill. We examined the feasibility and safety of stress imaging using an anti-gravity treadmill in patients with perceived poor exercise capacity.

Methods and results

49 patients were recruited for stress testing by anti-gravity treadmill (n = 29) or to a regadenoson control group (n = 20). Seventeen anti-gravity test patients (59%) reached target heart rate obviating the need for a pharmacologic stress agent. Adverse effects of the anti-gravity treadmill were limited to minor muscle aches in 5 subjects. Stress myocardial perfusion image quality judged by 3 blinded readers on a 5-point scale was comparable for the anti-gravity treadmill (4.30 ± SD 0.87) vs pharmacologic stress (4.28 ± SD 0.66).

Conclusion

Stress testing using an anti-gravity treadmill is feasible and may help some patients safely achieve target heart rate.

     

Treadmill ergometry and heart-volumes in elite biathletes: a longitudinal study

In a retrospective study in elite biathletes we investigated to what extent spiroergometric data, determinations of the anaerobic threshold and measurements of heart volume were related to former training programs, respectively subsequent achievements in competition. Between 1980 and 1987 top athletes of international (team A) as well as of national class (team B) underwent maximal graded treadmill tests in the laboratory. Twice a year maximal oxygen uptake (ml/kg.bw/min), maximal treadmill velocity (km/h), oxygen uptake and treadmill velocity at the anaerobic threshold (defined at 4 mmol/l lactate) were measured during maximal exercise, and absolute and relative heart-volume (heart volume/kg.bw) were evaluated at rest. Evaluation of ergospirometric and heart volume data revealed some relationship to various forms and intensities of training. Observations of team A athletes showed that up to 1985 there was a fairly good relationship between ergospirometry findings and achievements in competition during the following season. For heart volume, however, no such relationship could be found. The skating method introduced in cross-country skiing in 1985 gave more importance to the running technique than to absolute endurance capacity. From this time on the predictive value of laboratory tests clearly diminished.     

Hydroelectrolytic balance of Brazilian jiu-jitsu athletes during a simulated competition

Purpose

To analyze the hydroelectrolytic balance of Brazilian jiu-jitsu athletes during a simulated competition.

Methods

Eight athletes were analyzed in simulated competition (four matches of 10 min). Blood lactate and rating of perceived exertion (6–20 scale) were used to infer the intensity of the matches. Blood samples were taken to determine the serum levels of osmolality, total protein and some electrolytes (chlorides, sodium, potassium, calcium, magnesium, phosphorus and iron).

Results

The lactate concentration changed during the simulated competition (F _7.49 = 35.5; P < 0.001; η ² = 0.85), with an increase post-match compared to the pre-match in matches 1, 2 and 4, but not for match 3. For rating of perceived exertion, no changes were found during the competition (F _3.21 = 9.4; P = 0.440; η ² = 0.12). The matches did not change the osmolality, chlorides, sodium, potassium, magnesium and iron values. For total protein, a difference was observed between the time-points (F _{2.8; 19.6} = 4.6; P = 0.015; η ² = 0.40), with lower concentrations in pre-match 2 than pre-match 1, post-matches 2 and 3. The calcium concentration was also affected by the simulated competition (F _7.49 = 4.0; P = 0.002; η ² = 0.37), with values lower in pre-match 2 than post-matches 1 and 2. The phosphorus serum was changed by matches (F _{3.1; 21.7} = 18.6; P < 0.001; η ² = 0.73), with post-match 1 values higher than the pre-matches 1, 2, 3 and 4 and post-match 3. The pre-match 4 values were lower than post-matches 2 and 4.

Conclusion

Although there were some changes during simulated competition, important alterations in the hydroelectrolytic balance did not occur.

     

Stress injury of the lunate in tennis players: a case series and related biomechanical considerations

Objective

To investigate clinical and imaging differential diagnosis and tennis stroke biomechanics potentially involved in lunate stress injury pathogenesis.

Methods

The present report describes five competitive tennis players with overuse‐related dorsal wrist pain assessed by magnetic resonance imaging.

Results

Magnetic resonance imaging revealed the presence of lunate stress injury. All players were treated conservatively, with symptom resolution and complete functional recovery achieved at 14 weeks.

Conclusions

Lunate stress injuries should be considered in the differential diagnosis of overuse‐related dorsal wrist pain in tennis players.Wrist injuries are common among tennis players. They have been reported as the cause of 12.6% of on‐site withdrawals from the professional men''s circuit,¹ and the wrist is also the upper limb joint most often affected during Grand Slam tournaments.² In tennis players in general, most wrist injuries occur due to chronic overuse.³Players often complain of dorsal wrist pain, which can in turn disrupt training and competition. The present report describes five cases of overuse‐related dorsal wrist pain in tennis players, in whom MRI imaging studies revealed the presence of a lunate stress injury. To the best of our knowledge, this entity has not been previously analysed. Differential diagnoses and tennis stroke biomechanics potentially involved in lunate stress injuries pathogenesis are also discussed.     

Physical performance changes after unsupervised training during the autumn/spring semester break in competitive tennis players

Background

All competitive tennis players take time away from coaches throughout the year; however, little information is available as to the short‐term physiological effect of these breaks.

Objective

The purpose of this investigation was to evaluate the impact of a 5 week off‐campus structured, yet unsupervised, break from regular training in top collegiate tennis players.

Methods

A nationally ranked collegiate NCAA Division I male tennis team (n = 8) performed a test battery in December and again in January after a 5 week period of recommended, yet unsupervised, training. The tests performed were 5, 10 and 20 m sprints, spider agility test, medicine ball power throws, standing long jump, Wingate anaerobic power test, VO_2max, push‐up and sit‐up test, grip strength and range of motion (ROM) measures (goniometer) of the shoulder, hip, hamstring and quadriceps.

Results

Paired t tests (p<0.05) showed significant decreases in mean (SEM) Wingate power measurements in Watts/kg (pre: 8.35 (0.19) w/kg ; post: 7.80 (0.24) w/kg ), minimum Wingate power (pre: 5.89 (0.27) w/kg; post: 5.10 (0.38) w/kg) and VO_2max values (pre: 53.90 (1.11) ml/kg/min; post: 47.86 (1.54) ml/kg/min). A significant increase was seen in the athlete''s fatigue index (pre: 44.26 (2.85)%; post: 51.41 (3.53)%), fastest 5 m (pre: 1.07 (0.03) s; post: 1.12 (0.02) s), 10 m (pre: 1.79 (0.03) s; post: 1.84 (0.04) s) and 20 m (pre: 3.07 (0.05) s; post: 3.13 (0.05) s) sprint times. No significant differences were seen for the other variables tested.

Conclusions

These results suggest that a 5 week interruption of normal training can result in significant reductions in speed, power and aerobic capacity in competitive tennis players, likely owing to poor compliance with the prescribed training regimen. Therefore, coaches and trainers might benefit from techniques (eg, pre‐ and post‐testing) requiring athletes'' to have accountability for unsupervised workouts.Training for competitive tennis requires year‐long training in all aspects of physical performance. Throughout the training cycle, there will be periods where the athlete will be away from the home facility, coaches and medical staff and could reduce training volume or intensity without continual supervision. This period is not usually designed for competitive tournaments, yet substantial training is still planned and expected. The US Collegiate tennis environment provides opportunities to study these short‐term breaks from regular supervised training. The collegiate tennis season is divided into three distinct periods: autumn, spring and summer. Autumn (August–December) is the traditional pre‐season where training is designed to improve performance variables and training volume is high. Spring (February–May) is the major competition period. Between the autumn and spring, most programs allow their athletes to leave campus to see family and friends during the 3–5 week break period. This time period will be referred to as the “break”.A number of physiological variables are important in tennis play including speed, agility, strength, muscular endurance, anaerobic power, aerobic capacity and joint specific flexibility.^1,2,3 These are variables that could result in impaired performance if inadequate training takes place over the break that would result in performance akin to detraining.It has been shown that maximal measures (VO_2max, speed) can be maintained up to 28 days with a reduced training volume of 70%–80% of pre‐reduction training.⁴ If the athletes perform less than is required to maintain these values, aerobic capacity (VO_2max) can decline between 4–14% in as little as 4 weeks.⁵Power output has been shown to be reduced in as little as 3 weeks of strength training cessation.⁶ However, single movement explosive activity (vertical jump) has been shown to no be affected by 6 weeks cessation of training.⁶To date, no data are available describing the tennis athletes'' physiological response to a typical off‐campus autumn/spring break period. Therefore, the purpose of this study was to observe how unsupervised, yet “prescribed” training (3 days a week strength training program and 2 day/week speed and conditioning program) during a 5 week period between the autumn and spring seasons could impact physiological variables in high level NCAA Division I collegiate male tennis players'' upon returning to campus.     

Comparaison des données bioénergétiques observées lors d''un exercice musculaire sur bicyclettes équipées de plateaux rond ou «Harmonic

Introduction

In order to “harmonise” the constraints of pedalling (attenuate top dead centre and bottom dead centre), a non circular chain ring called “Harmonic” has been put on the market. The purpose of this study is to understand bioenergetic repercussions of this type of non circular chain ring during muscular exercise upon a bicycle.

Method

Thirteen regional level cyclists took part in this study. Each subject performed two maximal oxygen uptake exercise tests, one with a circular chain ring, the other with a “Harmonic” chain ring with the same cogwheel (52 tooth). They were performed on a cyclo-simulator. Speeds (km·h^t-1) and/or simulated slopes (%) increased every 2 min 30 s. They were, respectively: 28-2, 30-2, 35-2, 37.5-2, 40-2, 40-3, 42.5-3. O₂ uptake (VO₂), pulmonary ventilation and heart rate were measured continuously; and blood lactate concentration was measured during the last 30 s of each level.

Results

Regardless of speeds and slopes, there was no significant difference for VO₂, pulmonary ventilation, heart rate and blood lactate concentration between the two chain rings.

Conclusion

If the chain ring in question is supposed to attenuate top dead centre and bottom dead centre pedalling, it does not present any lessened energy expenditure during muscular exercise.     

Effects of three different water temperatures on dehydration in competitive swimmers

Aims

The purpose of this study was to evaluate the effects of three different water temperatures on physiological responses (dehydration, sweat rate, urine output, rectal temperature and plasma electrolytes) of competitive athletes during a “simulated” race of 5 km in an indoor swimming pool.

Methods

Nine male competitive master swimmers swam 5 km with the water at temperatures of 23, 27 and 32 ?C. Immediately before (Pre) and after (Post) each trial, samples of blood and urine were collected, body weight was recorded and rectal temperature was measured. The dehydration percentage and sweat rate were the highest at 32 ?C and the lowest at 23 ?C (23 ?C: −0.9 ± 0.5; 27 ?C: −1.3 ± 0.6; 32 ?C: −2.2 ± 0.7% and 23 ?C: 0.48 ± 0.28; 27 ?C: 0.76 ± 0.36; 32 ?C: 1.25 ± 0.37 l/h). The Post urine volume output was not significantly different in the three trials (23 ?C: 122.6 ± 62.4; 27 ?C: 78.2 ± 24.9; 32 ?C 81.4 ± 37.0 mL). The 27 and 32 ?C water increased the rectal temperature (Pre: 37.0 ± 0.3; Post: 37.9 ± 0.5 ?C–Pre: 36.9 ± 0.4; Post: 38.0 ± 0.4 ?C, respectively).

Results

This study shows that dehydration, sweat rate and body temperatures simultaneously increase with the rise of water temperature during the shortest open water swimming event distance (5 km) performed at race intensity.     

Postreperfusion myocardial technetium-99m-sestamibi defect corresponds to area at risk: experimental results from an ischemia-reperfusion porcine model

Introduction

Technetium-99m–sestamibi (MIBI) is the most frequently used myocardial perfusion tracer in patients with ischemic heart disease. In patients with acute ST-elevation myocardial infarction, we previously found that the defect in myocardial MIBI uptake was the same in patients injected with MIBI before primary angioplasty and in patients injected immediately after successful treatment. Thus, reperfusion may not be followed by increased uptake of MIBI. Instead, the MIBI defect after reperfusion may reflect the area at risk (AAR) defined by MIBI injected before treatment. We intended to investigate whether myocardial imaging with MIBI administered after reperfusion reflects myocardial perfusion or rather the ischemic AAR.

Methods

In 12 pigs, left anterior descending coronary artery was totally occluded for 45 min with an angioplasty balloon. After a 2-h reperfusion, MIBI was injected intravenously, and ¹⁵³Gd-microspheres were injected in left atrium. AAR and infarct size (IS) were determined by histochemical staining. MIBI and microsphere distribution were evaluated by counting the sliced left ventricle on a gamma camera. Defects were defined as uptake less than 45% of maximum uptake.

Results

The mean±S.D. defect size as a fraction of left ventricle was for MIBI 21%±5.5%, AAR 25%±6.3%, IS 13%±3.9% and microspheres defect size 7.3%±5.5%. MIBI defect size overestimated IS (P=.0005) and microspheres defect size (P=.0001), but it was not significantly different from AAR (P=.30).

Conclusion

In a porcine model of myocardial infarction after 45 min of ischemia, MIBI administered 120 min after reperfusion delineates AAR.     

An integrated physiological and performance profile of professional tennis

Objective

To describe the physiological responses to tournament tennis in relation to prevailing environmental conditions, match notation, and skills that underpin performance.

Design

14 male professional tennis players (mean (SD) age, 21.4 (2.6) years; height, 183.0 (6.9) cm; body mass, 79.2 (6.4) kg) were studied while contesting international tennis tournaments. Environmental conditions, match notation, physiological (core temperature, hydration status, heart rate, blood variables), and performance indices (serve kinematics, serve velocity, error rates) were recorded.

Results

Hard and clay court tournaments elicited similar peak core temperature (38.9 (0.3) v 38.5 (0.6)°C) and average heart rate (152 (15) v 146 (19) beats/min) but different body mass deficit (1.05 (0.49) v 0.32 (0.56)%, p<0.05). Average pre‐match urine specific gravity was 1.022 (0.004). Time between points was longer during hard court matches (25.1 (4.3) v 17.2 (3.3) s, p<0.05). Qualitative analysis of first and second serves revealed inverse relations between the position of the tossing arm at ball release and the position of the ball toss and progressive match time (respectively, r = −0.74 and r = −0.73, p<0.05) and incurred body mass deficit (r = 0.73 and r = 0.73, p<0.05).

Conclusions

Participants began matches in a poor state of hydration, and experienced moderate thermoregulatory strain and dehydration during competition. These adverse physiological conditions may compromise performance and influence notational analyses.     

High-resolution phase-contrast MRI of aortic and pulmonary blood flow during rest and physical exercise using a MRI compatible bicycle ergometer

Purpose

To establish high-resolution phase-contrast magnetic resonance imaging (PC-MRI) using a MRI compatible bicycle ergometer to quantify aortic and pulmonary blood flow during resting conditions and exercise.

Materials and methods

In 20 healthy volunteers (mean age, 26.8 ± 5.0 years) high-resolution PC-MRI (mean temporal resolution, 7.4 ± 3.2 ms) was performed in the ascending aorta (AA) and main pulmonary artery (PA) during physical rest and three exercise stages: stage 1, no-load operation; stage 2, heart rate increase 40% compared to rest; stage 3, heart rate increase 80% compared to rest. Flow quantification in AA and PA included flow volume (FV), average velocity (AV), peak velocity (PV) and time to PV (TP).

Results

In stage 1 only TP demonstrated a significant change. With progression to stage 2, all parameters altered significantly. Flow measurements during stage 3 evidenced further alterations only of AV and TP regarding both AA and PA. The deviation of the heart rate from the desired target value was significantly higher for stage 3 compared to stage 2, and 15% of the subjects did not reach the desired target heart rate of stage 3 at all.

Conclusion

Flow quantification by high-resolution PC-MRI during exercise using a MRI compatible bicycle ergometer is feasible. Medium exercise stages are necessary and sufficient to demonstrate flow alterations in healthy volunteers. PC-MRI ergometry may give insights into aberrant hemodynamic conditions in patients with cardiovascular and pulmonary disease.