Effect of hyperoxic-supplemented interval training on endurance performance in trained cyclists

The aim of this study was to determine the effect of hyperoxic-supplemented interval training on endurance performance. Using a single-blind, randomised control-trial design, 16 well-trained cyclists were randomly assigned to either hyperoxic or normoxic training. Participants visited the laboratory twice per week, for 4 weeks, to perform high-intensity interval training sessions. A 20 km TT, incremental exercise test and 60s all-out test were conducted pre- and post-intervention. Smaller effects for most physiological measures, including VO 2peak (1.9 ± 4.3%) and lactate threshold (0.3 ± 8.3%), were observed after training in hyperoxia compared to normoxia. There was a small increase in mean power during the 20 km TT after hyperoxia [2.1 ± 3.7%; effect size (ES): - 0.30 ± 0.39] but this was less than that observed after normoxia (4.9 ± 3.9%; ES: - 0.44 ± 0.60). During the 60 s all-out test, the peak relative power was relatively unchanged, whereas mean relative power was increased in normoxia (2.3 ± 3.4%) but not hyperoxia (0.3 ± 1.2%; ES: - 0.34 ± 0.49). Hyperoxic-supplemented interval training in the competitive season had less effect on endurance and high-intensity performance and physiology in trained endurance cyclists compared to interval training in normoxia. Therefore hyperoxic-supplemented training at sea level appears to be not worthwhile for maximising performance in competitive endurance athletes.     

Interval training program optimization in highly trained endurance cyclists

PURPOSE: The purpose of this study was to examine the influence of three different high-intensity interval training (HIT) regimens on endurance performance in highly trained endurance athletes. METHODS: Before, and after 2 and 4 wk of training, 38 cyclists and triathletes (mean +/- SD; age = 25 +/- 6 yr; mass = 75 +/- 7 kg; VO(2peak) = 64.5 +/- 5.2 mL x kg(-1) min(-1)) performed: 1) a progressive cycle test to measure peak oxygen consumption (VO(2peak)) and peak aerobic power output (PPO), 2) a time to exhaustion test (T(max)) at their VO(2peak) power output (P(max)), as well as 3) a 40-km time-trial (TT(40)). Subjects were matched and assigned to one of four training groups (G(2), N = 8, 8 x 60% T(max) at P(max), 1:2 work:recovery ratio; G(2), N = 9, 8 x 60% T(max) at P(max), recovery at 65% HR(max); G(3), N = 10, 12 x 30 s at 175% PPO, 4.5-min recovery; G(CON), N = 11). In addition to G(1), G(2), and G(3) performing HIT twice per week, all athletes maintained their regular low-intensity training throughout the experimental period. RESULTS: All HIT groups improved TT(40) performance (+4.4 to +5.8%) and PPO (+3.0 to +6.2%) significantly more than G(CON) (-0.9 to +1.1%; P < 0.05). Furthermore, G(1) (+5.4%) and G(2) (+8.1%) improved their VO(2peak) significantly more than G(CON) (+1.0%; P < 0.05). CONCLUSION: The present study has shown that when HIT incorporates P(max) as the interval intensity and 60% of T(max) as the interval duration, already highly trained cyclists can significantly improve their 40-km time trial performance. Moreover, the present data confirm prior research, in that repeated supramaximal HIT can significantly improve 40-km time trial performance.     

Sperm characteristics of endurance trained cyclists

The purpose of this study was to investigate the influence of cycling on sperm characteristics. Twenty subjects volunteered for the study, comprising 10 long distance competitive cyclists (median 25.5 y) and 10 sedentary controls (median 24.5 y). A questionnaire was used to obtain a history of training, health, nutrition and life style. Semen analysis consisted of a detailed evaluation of sperm characteristics that included semen volume, sperm count, viability, motility and morphology. Compared to controls, the cyclists had a significantly lower proportion of spermatozoa with normal morphology (medians: 41.5 % versus 19.5 %; p < 0.01) and a significantly higher proportion of morphologically abnormal tapered forms (medians: 4.5 % versus 22.5 %; p < 0.01). No significant difference in semen volume and sperm motility, viability and count was observed between the two groups. We concluded that endurance cycling appears to be associated with a significant alteration in sperm morphology.     

Effects of resistance training on endurance capacity and muscle fiber composition in young top-level cyclists

Equivocal findings exist on the effect of concurrent strength (S) and endurance (E) training on endurance performance and muscle morphology. Further, the influence of concurrent SE training on muscle fiber-type composition, vascularization and endurance capacity remains unknown in top-level endurance athletes. The present study examined the effect of 16 weeks of concurrent SE training on maximal muscle strength (MVC), contractile rate of force development (RFD), muscle fiber morphology and composition, capillarization, aerobic power (VO2max), cycling economy (CE) and long/short-term endurance capacity in young elite competitive cyclists (n=14). MVC and RFD increased 12-20% with SE (P<0.01) but not E. VO2max remained unchanged. CE improved in E to reach values seen in SE. Short-term (5-min) endurance performance increased (3-4%) after SE and E (P<0.05), whereas 45-min endurance capacity increased (8%) with SE only (P<0.05). Type IIA fiber proportions increased and type IIX proportions decreased after SE training (P<0.05) with no change in E. Muscle fiber area and capillarization remained unchanged. In conclusion, concurrent strength/endurance training in young elite competitive cyclists led to an improved 45-min time-trial endurance capacity that was accompanied by an increased proportion of type IIA muscle fibers and gains in MVC and RFD, while capillarization remained unaffected.     

Inspiratory muscle fatigue in trained cyclists: effects of inspiratory muscle training

PURPOSE: This study evaluated the influence of simulated 20- and 40-km time trials upon postexercise inspiratory muscle function of trained competitive cyclists. In addition, we examined the influence of specific inspiratory muscle training (IMT) upon the responses observed. METHODS: Using a double-blind placebo-controlled design, 16 male cyclists (mean +/- SEM VO2max 64 +/- 2 mL.kg-1.min-1) were assigned randomly to either an experimental (IMT) or sham-training control (placebo) group. Maximum static and dynamic inspiratory muscle function was assessed immediately pre- and <2, 10, and 30 min post-simulated 20- and 40-km time trials before and after 6-wk of IMT or sham-IMT. RESULTS: Maximum inspiratory mouth pressure (P0) measured within 2 min of completing the 20- and 40-km time trial rides was reduced by 18% and 13%, respectively, and remained below preexercise values at 30 min. The 20- and 40-km time trials induced a reduction in inspiratory flow rate at 30% P0 by 14% and 6% in the IMT group versus 13% and 7% for the placebo group, and also remained below preexercise values at 30 min. There was also a significant slowing of inspiratory muscle relaxation rate postexercise; these trends were almost completely reversed by 30 min postexercise. Significant improvements in 20- and 40-km time trial performance were seen (3.8 +/- 1.7% and 4.6 +/- 1.9%, respectively; P < 0.05) and postexercise reductions in muscle function were attenuated with IMT. CONCLUSION: These data support existing evidence that there is significant global inspiratory muscle fatigue after sustained heavy endurance exercise. Furthermore, the present study provides new evidence that performance enhancements observed after IMT are accompanied by a decrease in inspiratory muscle fatigue.     

Influence of endurance exercise on respiratory muscle performance

PURPOSE: During high-intensity, exhaustive, constant-load exercise above 85% of maximal oxygen consumption, the diaphragm of healthy subjects can fatigue. Although a decrease in trans-diaphragmatic pressure is the most objective measure of diaphragmatic fatigue, possible extra-diaphragmatic muscle fatigue would not be detected by this method. The aim of the present study was to investigate the impact of exhaustive, constant-load cycling exercise at different intensities on global respiratory performance determined by the time to exhaustion while breathing against a constant resistance. METHODS: Ten healthy, male subjects performed an exhaustive cycling endurance test at 65, 75, 85, and 95% of peak oxygen consumption (VO2peak). Before cycling (to) as well as at 10 min (t10) and 45 min (t45) after cycling, respiratory performance was determined. RESULTS: Breathing endurance was equivalently reduced after exhaustive cycling at either 65% (8.4 +/- 4.1 min [t0] vs 3.9 +/- 2.8 min [t10]), 75% (9.9 +/- 6.1 vs 4.4 +/- 2.8 min), 85% (9.3 +/- 6.0 vs 3.8 +/- 2.9 min), or 95% VO2peak (8.5 +/- 5.1 vs 4.0 +/- 2.5 min) and, therefore, was independent of exercise intensity. CONCLUSION: This result contradicts previous findings, possibly due to the fact that extra-diaphragmatic muscles are tested in addition to the diaphragm during resistive breathing.     

Resistive respiratory muscle training improves and maintains endurance swimming performance in divers.

Respiratory work is increased during exercise under water and may lead to respiratory muscle fatigue, which in turn can compromise swimming endurance. Previous studies have shown that respiratory muscle training, conducted five days per week for four weeks, improved both respiratory and fin swimming endurance. This training (RRMT-5) consisted of intermittent vital capacity breaths (twice/minute) against spring loaded breathing valves imposing static and resistive loads generating average inspiratory pressures of approximately 40 cmH2O and expiratory pressures of approximately 47 cmH2O. The purpose of the present study (n = 20) was to determine if RRMT 3 days per week (RRMT-3) would give similar improvements, and if continuing RRMT 2 days per week (RRMT-M) would maintain the benefits of RRMT-3 in fit SCUBA divers. Pulmonary function, maximal inspiratory (P(insp)) and expiratory pressures (P(exp)), respiratory endurance (RET), and surface and underwater (4 fsw) fin swimming endurance were determined prior to and after RRMT, and monthly for 3 months. Pulmonary function did not significantly improve after either RRMT-3 or RMMT-5; while P(insp) (20 and 15%) and P(exp) (25 and 11%), RET (73 and 217%), surface (50 and 33%) and underwater (88 and 66%) swim times improved. VO2, VE and breathing frequency decreased during the underwater endurance swims after both RRMT-3 and RRMT-5. During RRMT-M P(insp) and P(exp) and RET and swimming times were maintained at post RRMT-3 levels. RRMT 3 or 5 days per week can be recommended to divers to improve both respiratory and fin swimming endurance, effects which can be maintained with RRMT twice weekly.     

The ventilatory threshold, heart rate, and endurance performance: relationships in elite cyclists

The purpose of this study was to investigate the validity of the ventilatory response during incremental exercise as indication of endurance performance during prolonged high-intensity exercise under field test conditions in elite cyclists. The ventilatory threshold (VT) was assessed in 14 male elite cyclists (age 22.4+/-3.4 years, height 181+/-6 cm, weight 69.2+/-6.8 kg, VO2max 69+/-7 ml x min(-1) x kg(-1)) during an incremental exercise test (20 W x min(-1)). Heart rate and oxygen uptake were assessed at the following ventilatory parameters: 1. Steeper increase of VCO2 as compared to VO2 (V-slope-method); 2. Respiratory exchange ratio (RQ)=0.95 and 1.00; 3. VE/VO2 increase without a concomitant VE/VCO2 (VE/VO2 method). Three weeks following the laboratory tests, the ability to maintain high-intensity exercise was determined during a 40 km time trial on a bicycle. During this time trial the mean heart rate (HR(TT)) and the road racing time (TT) were assessed. The V-slope-method and the VE/VO2 method showed significant correlations with TT (V-slope: r = -0.82; p<0.001; 90% interval of confidence = +/-82 sec; VE/VO2: r=-0.81; p<0.01; 90% interval of confidence = +/-81 sec). Heart rate at the ventilatory parameters and at the maximum heart rate (HRmax) showed significant correlations with HR(TT). The V-slope-method is the preferred method to predict heart rate during prolonged high-intensity exercise (r=0.93; p<0.0001; 90% interval of confidence: +/-4.8 beats x min(-1)). For predicting heart rate during prolonged high-intensity exercise using an incremental exercise test (20 W x min(-1)), without the knowledge of ventilatory parameters, we recommend using the regression formula: H(TT)=0.84 x Hmax + 14.3 beats x min(-1) (r=0.85; p<0.001).     

Adaptations to training in endurance cyclists: implications for performance.

Our present scientific knowledge of the effects of specific training interventions undertaken by professional cyclists on selected adaptive responses in skeletal muscle and their consequences for improving endurance performance is limited: sport scientists have found it difficult to persuade elite cyclists to experiment with their training regimens and access to muscle and blood samples from these athletes is sparse. Owing to the lack of scientific study we present a theoretical model of some of the major training-induced adaptations in skeletal muscle that are likely to determine performance capacity in elite cyclists. The model includes, but is not limited to, skeletal muscle morphology, acid-base status and fuel supply. A working premise is that the training-induced changes in skeletal muscle resulting from the high-volume, high-intensity training undertaken by elite cyclists is at least partially responsible for the observed improvements in performance. Using experimental data we provide evidence to support the model.     

Effects of respiratory muscle endurance training on wheelchair racing performance in athletes with paraplegia: a pilot study.

OBJECTIVE: Respiratory muscle endurance training (RMET) has been shown to improve both respiratory muscle and cycling exercise endurance in able-bodied subjects. Since effects of RMET on upper extremity exercise performance have not yet been investigated, we evaluated the effects of RMET on 10-km time-trial performance in wheelchair racing athletes. DESIGN: Pilot study, controlled before and after trial. SETTING: Spinal cord injury research center. PARTICIPANTS: 12 competitive wheelchair racing athletes. INTERVENTIONS: The training group performed 30 sessions of RMET for 30 min each. The control group did no respiratory muscle training. MAIN OUTCOME MEASUREMENTS: Differences in 10-km time-trial performance pre- versus postintervention. RESULTS: In the training group, the time of the 10-km time-trial decreased significantly from before versus after intervention (27.1 +/- 9.0 vs. 24.1 +/- 6.6 min); this did not occur in the control group (23.3 +/- 2.8 vs. 23.2 +/- 2.4 min). No between groups difference was present (P = 0.150). Respiratory muscle endurance increased significantly within the training group (9.1 +/- 7.2 vs. 39.9 +/- 17.8 min) and between groups, but not within the control group (4.3 +/- 2.9 vs. 6.6 +/- 7.0 min) before versus after intervention. CONCLUSION: There was a strong trend, with a large observed effect size of d = 0.87, towards improved performance in the 10-km time-trial after 6 weeks of RMET.     

Effects of endurance training on the isocapnic buffering and hypocapnic hyperventilation phases in professional cyclists

OBJECTIVES: To evaluate the changes produced in both the isocapnic buffering and hypocapnic hyperventilation (HHV) phases of professional cyclists (n = 11) in response to endurance training, and to compare the results with those of amateur cyclists (n = 11). METHODS: Each professional cyclist performed three laboratory exercise tests to exhaustion during the active rest (autumn: November), precompetition (winter: January), and competition (spring: May) periods of the sports season. Amateur cyclists only performed one exercise test during the competition period. The isocapnic buffering and HHV ranges were calculated during each test and defined as Vo2 and power output (W). RESULTS: No significant differences were found in the isocapnic buffering range in each of the periods of the sports season in professional cyclists. In contrast, there was a significant reduction in the HHV range (expressed in W) during both the competition (p<0.01) and precompetition(p<0.05) periods compared with the rest period. On the other hand, a longer HHV range (p<0.01) was observed in amateur cyclists than in professional cyclists (whether this was expressed in terms of Vo2 or W). CONCLUSIONS: No change is observed in the isocapnic buffering range of professional cyclists throughout a sports season despite a considerable increase in training loads and a significant reduction in HHV range expressed in terms of power output.     

Effects of strength training on lactate threshold and endurance performance

To determine the effects of 12 wk of strength training on lactate threshold (LT) and endurance performance, 18 healthy untrained males between 25 and 34 yr of age were randomly assigned to either strength training (N = 10) or control (N = 8) groups. Despite no changes in treadmill VO2max or cycle peak VO2, a 33 +/- 5% increase (P less than 0.001) in cycling time to exhaustion at 75% of peak VO2 was observed following training. No significant changes in cycling time were observed in the control group. There were significant reductions in plasma lactate concentration at all relative exercise intensities ranging between 55 and 75% of peak VO2 training. The improved endurance performance was associated with a 12% increase in LT (r = 0.78, P less than 0.001). The strength training program resulted in significant improvements (P less than 0.001) of 31 +/- 5% and 35 +/- 7% in isokinetic peak torque values for leg extension and flexion, respectively, at a velocity of 30 degrees.s-1. There were also significant increases in 1-RM values of 30 +/- 4% (P less than 0.001) for leg extension, 52 +/- 6% (P less than 0.001) for leg flexion, and 20 +/- 4% (P less than 0.001) for the bench press. These findings indicate that strength training improves cycle endurance performance independently of changes in VO2max. This improved performance appears to be related to increases in LT and leg strength.     

Effects of 12 weeks of block periodization on performance and performance indices in well‐trained cyclists

The purpose of this study was to compare the effects of two different methods of organizing endurance training in trained cyclists during a 12‐week preparation period. One group of cyclists performed block periodization (BP; n = 8), wherein every fourth week constituted five sessions of high‐intensity aerobic training (HIT), followed by 3 weeks of one HIT session. Another group performed a more traditional organization (TRAD; n = 7), with 12 weeks of two weekly HIT sessions. The HIT was interspersed with low‐intensity training (LIT) so that similar total volumes of both HIT and LIT were performed in the two groups. BP achieved a larger relative improvement in VO_2max than TRAD (8.8 ± 5.9% vs 3.7 ± 2.9%, respectively, P < 0.05) and a tendency toward larger increase in power output at 2 mmol/L [la^?] (22 ± 14% vs 10 ± 7%, respectively, P = 0.054). Mean effect size (ES) of the relative improvement in VO_2max, power output at 2 mmol/L [la^?], hemoglobin mass, and mean power output during 40‐min all‐out trial revealed moderate superior effects of BP compared with TRAD training (ES range was 0.62–1.12). The present study suggests that BP of endurance training has superior effects on several endurance and performance indices compared with TRAD.     

The effects of strength training on endurance performance and muscle characteristics.

PURPOSE: The purpose of this study was to determine the effects of resistance training on endurance performance and selected muscle characteristics of female cyclists. METHODS: Twenty-one endurance-trained, female cyclists, aged 18-42 yr, were randomly assigned to either a resistance training (RT; N = 14) or a control group (CON; N = 7). Resistance training (2X x wk(-1)) consisted of five sets to failure (2-8 RM) of parallel squats for 12 wk. Before and immediately after the resistance-training period, all subjects completed an incremental cycle test to allow determination of both their lactate threshold (LT) and peak oxygen consumption VO2). In addition, endurance performance was assessed by average power output during a 1-h cycle test (OHT), and leg strength was measured by recording the subject's one repetition maximum (1 RM) concentric squat. Before and after the 12-wk training program, resting muscle was sampled by needle biopsy from m. vastus lateralis and analyzed for fiber type diameter, fiber type percentage, and the activities of 2-oxoglutarate dehydrogenase and phosphofructokinase. RESULTS: After the resistance training program, there was a significant increase in 1 RM concentric squat strength for RT (35.9%) but not for CON (3.7%) (P < 0.05). However, there were no significant changes in OHT performance, LT, VO2, muscle fiber characteristics, or enzyme activities in either group (P > 0.05). CONCLUSION: The present data suggest that increased leg strength does not improve cycle endurance performance in endurance-trained, female cyclists.     

Effects of different types of respiratory muscle training on exercise performance in runners

To compare two different types of respiratory muscle training on exercise performance, a protocol was devised consisting of a combination of a 4-week, 12-session resistive respiratory muscle training (RRMT) followed by a 4-week, 12-session voluntary isocapnic hyperpnea training (VIHT) and conducted in experienced runners (4 men, 4 women). Measurements before and 5 days after training included: pulmonary function (spirometry), maximal inspiratory and expiratory mouth pressures, respiratory endurance time, maximal oxygen uptake (V(o2)max), running time to voluntary exhaustion at 80% V(o2)max, blood lactate concentration, and minute ventilation. There were no statistically significant differences in pulmonary functions and V(o2)max post-RRMT and post-VIHT compared to pre-RMT. Following RRMT the inspiratory muscle strength had improved by 23.8 +/- 30% and 18.7 +/- 21.4% at rest and immediately after the running test, respectively. RRMT did not increase the time intense voluntary isocapnic ventilation could be maintained during rest while VIHT increased it (237 +/- 207.8%). The duration of the endurance run was extended 17.7 +/- 6.5% after RRMT and 45.5 +/- 14.3% after VIHT.     

Effects of submaximal and supramaximal interval training on determinants of endurance performance in endurance athletes

We compared the effects of submaximal and supramaximal cycling interval training on determinants of exercise performance in moderately endurance‐trained men. Maximal oxygen consumption (VO_2max), peak power output (P_peak), and peak and mean anaerobic power were measured before and after 6 weeks (3 sessions/week) of submaximal (85% maximal aerobic power [MP], HIIT₈₅, n = 8) or supramaximal (115% MP, HIIT₁₁₅, n = 9) interval training to exhaustion in moderately endurance‐trained men. High‐intensity training volume was 47% lower in HIIT₁₁₅ vs HIIT₈₅ (304 ± 77 vs 571 ± 200 min; P < 0.01). Exercise training was generally associated with increased VO_2max (HIIT₈₅: +3.3 ± 3.1 mL/kg/min; HIIT₁₁₅: +3.3 ± 3.6 ml/kg/min; Time effect P = 0.002; Group effect: P = 0.95), P_peak (HIIT₈₅: +18 ± 9 W; HIIT₁₁₅: +16 ± 27 W; Time effect P = 0.045; Group effect: P = 0.49), and mean anaerobic power (HIIT₈₅: +0.42 ± 0.69 W/kg; HIIT₁₁₅: +0.55 ± 0.65 W/kg; Time effect P = 0.01; Group effect: P = 0.18). Six weeks of submaximal and supramaximal interval training performed to exhaustion seems to equally improve VO_2max and anaerobic power in endurance‐trained men, despite half the accumulated time spent at the target intensity.     

Effects of short-term endurance training on muscle deoxygenation trends using NIRS

PURPOSE: This study examined changes in cardiorespiratory responses and muscle deoxygenation trends to test the hypothesis that both central and peripheral adaptations would contribute to the improvements in VO(2max) and simulated cycling performance after short-term high-intensity training. METHODS: Eight male cyclists performed an incremental cycle ergometer test to voluntary exhaustion, and a simulated 20-km time trial (20TT) on wind-loaded rollers before and after training (60 min x 5 d x wk(-1) x 3 wk at 85-90% VO(2max). Near-infrared spectroscopy (NIRS) was used to evaluate the trend in vastus medialis hemoglobin/myoglobin deoxygenation (Hb/Mb-O(2) during both tests pre- and post-training. RESULTS: Training induced significant increases (P 0.05) in the VO(2) (4.02 +/- 0.52 to 4.04 +/- 0.51), heart rate (176 +/- 9 to 173 +/- 8 beats x min ) or O pulse (22.4 +/- 3.2 to 23.5 +/- 2.8 mL O(2) x beat(-1)). However, mean muscle deoxygenation during the 20TT was significantly lower after training (-550 +/- 292 to -707 +/- 227 mV, P 相似文献   

No effect of a noradrenergic reuptake inhibitor on performance in trained cyclists

INTRODUCTION: According to the central fatigue hypothesis, serotonin (5-HT) is related to fatigue, whereas the noradrenergic system is primarily concerned with arousal and motivation, and therefore hypothesized to enhance performance. The purpose of the present study was to examine the effects of a selective noradrenergic reuptake inhibitor (reboxetine 2 x 4 mg REB-NARI) on exercise performance. METHODS: Seven healthy well-trained male cyclists (age: 23 +/- 1.7 yr, height: 182 +/- 5.8 cm, weight: 73.5 +/- 8.5 kg, VO2max: 73.5 +/- 6.4 mL x kg(-1) x min(-1), Watt(max): 376 +/- 11.7 W) participated to the study. Subjects completed two endurance tests (time trials) starting at 65% Wmax in a double-blind randomized cross-over design. Blood samples were collected for adrenocorticotropin, prolactin, cortisol, growth hormone (GH), beta-endorphins, and catecholamines and were taken at 30-min time intervals until the end of exercise. Performance was analyzed with a paired t-test, whereas data for hormonal and metabolic differences during the trials were analyzed using an ANOVA repeated measures design and an LSD-planned comparisons test. Significance level was set at P < 0.05. RESULTS: Performance was not influenced by the NARI (REB: 97 min +/- 3 min, placebo (PLAC): 92 min +/- 1 min). All hormones increased during exercise except for GH in the REB trial, which was significantly lower than PLAC. The other hormones were significantly higher in the REB trial versus the PLAC trial at the end of exercise and during recovery. CONCLUSION: In conclusion, the results demonstrate that the drug had a central effect. In particular, the higher resting GH concentrations indicated a marked and selective noradrenergic effect of REB. However, performance was not influenced by a selective NARI in well-trained endurance athletes.     

Neural, metabolic, and performance adaptations to four weeks of high intensity sprint-interval training in trained cyclists

The purpose of this study was to investigate the effects of short-term, high-intensity sprint training on the root mean squared (RMS) and median frequency (MF) derived from surface electromyography (EMG), as well as peak power, mean power, total work, and plasma lactate levels in trained cyclists when performed concurrently with endurance training. Seventeen trained cyclists were randomly assigned to a sprint training (S) group (n = 10, age 25 +/- 2.0 y) or a control (C) group (n = 7, age 25 +/- 0.5 y). Sprint training was performed bi-weekly for four weeks, comprising a total of 28 min over the training period. EMG measurements were taken before and after training during a series of four 30-s sprints separated by four minutes of active recovery. Plasma lactate, peak power, mean power, and total work were measured during each sprint bout. Following sprint training a significant increase occurred in the RMS of the vastus lateralis with a decrease in MF of the same muscle. Values for the vastus medialis did not change. Pre training exercising plasma lactate values were higher (p < 0.05) in C compared to S, but did not change with training. Exercising plasma lactate values increased (p < 0.05) from pre to post training in S, but were not different from C post training. Total work output increased from pre to post in S (p = 0.06). Peak power, mean power, and V.O (2)max increased (p < 0.05) pre to post training in S and C, indicating C was not a true control. In conclusion, these data suggest that four weeks of high-intensity sprint training combined with endurance training in a trained cycling population increased motor unit activation, exercising plasma lactate levels, and total work output with a relatively low volume of sprint exercise compared to endurance training alone.