Breathing a low-density gas reduces respiratory muscle force development and marginally improves exercise performance in master athletes.

INTRODUCTION: We tested the hypothesis that breathing heliox, to attenuate the mechanical constraints accompanying the decline in pulmonary function with aging, improves exercise performance. METHODS: Fourteen endurance-trained older men (67.9 ± 5.9 year, [Formula: see text]O2max: 50.8 ± 5.8 ml/kg/min; 151% predicted) completed two cycling 5-km time trials while breathing room air (i.e., 21% O2-79% N2) or heliox (i.e., 21% O2-79% He). Maximal flow-volume curves (MFVC) were determined pre-exercise to characterize expiratory flow limitation (EFL, % tidal volume intersecting the MFVC). Respiratory muscle force development was indirectly determined as the product of the time integral of inspiratory and expiratory mouth pressure (∫Pmouth) and breathing frequency. Maximal inspiratory and expiratory pressure maneuvers were performed pre-exercise and post-exercise to estimate respiratory muscle fatigue. RESULTS: Exercise performance time improved (527.6 ± 38 vs. 531.3 ± 36.9 s; P = 0.017), and respiratory muscle force development decreased during inspiration (- 22.8 ± 11.6%, P < 0.001) and expiration (- 10.8 ± 11.4%, P = 0.003) with heliox compared with room air. EFL tended to be lower with heliox (22 ± 23 vs. 30 ± 23% tidal volume; P = 0.054). Minute ventilation normalized to CO2 production ([Formula: see text]E/[Formula: see text]CO2) increased with heliox (28.6 ± 2.7 vs. 25.1 ± 1.8; P < 0.001). A reduction in MIP and MEP was observed post-exercise vs. pre-exercise but was not different between conditions. CONCLUSIONS: Breathing heliox has a limited effect on performance during a 5-km time trial in master athletes despite a reduction in respiratory muscle force development.

Single- Versus Double-Leg Cycling: Small Muscle Mass Exercise Improves Exercise Capacity to a Greater Extent in Older Compared With Younger Population.

Manipulating the amount of muscle mass engaged during exercise can noninvasively inform the contribution of central cardiovascular and peripheral vascular-oxidative functions to endurance performance. To better understand the factors contributing to exercise limitation in older and younger individuals, exercise performance was assessed during single-leg and double-leg cycling. 16 older (67 ± 5 years) and 14 younger (35 ± 5 years) individuals performed a maximal exercise using single-leg and double-leg cycling. The ratio of single-leg to double-leg cycling power (RatioPower SL/DL) was compared between age groups. The association between fitness (peak oxygen consumption, peak power output, and physical activity levels) and RatioPower SL/DL was explored. The RatioPower SL/DL was greater in older compared with younger individuals (1.14 ± 0.11 vs. 1.06 ± 0.08, p = .041). The RatioPower SL/DL was correlated with peak oxygen consumption (r = .886, p < .001), peak power output relative to body mass (r = .854, p < .001), and levels of physical activity (r = .728, p = .003) in the younger but not older subgroup. Reducing the amount of muscle mass engaged during exercise improved exercise capacity to a greater extent in older versus younger population and may reflect a greater reduction in central cardiovascular function compared with peripheral vascular-oxidative function with aging.

The Improvement in Exercise Performance during Reduced Muscle Mass Exercise is Associated with an Increase in Femoral Blood Flow in Older and Younger Endurance-Trained Athletes.

This study investigated whether the improved performance observed with maximal self-paced single-leg (SL), compared with double-leg (DL) cycling, is associated with enhanced femoral blood flow and/or altered tissue oxygenation. The hyperaemic response to exercise was assessed in younger and older athletes. Power output was measured in 12 older (65 ± 4 y) and 12 younger (35 ± 5 y) endurance-trained individuals performing 2 x 3 min maximal self-paced exercise using SL and DL cycling. Blood flow (BF) in the femoral artery was assessed using Doppler ultrasound and muscle oxygenation was measured using near-infrared spectroscopy on the vastus lateralis. SL cycling elicited a greater power output (295 ± 83 vs 265 ± 70 W, P < 0.001) and peak femoral BF (1749.1 ± 533.3 vs 1329.7 ± 391.7 ml/min, P < 0.001) compared with DL cycling. Older individuals had a lower peak BF in response to exercise (1355.4 ± 385.8 vs 1765.2 ± 559.6 ml/min, P = 0.019) compared with younger individuals. Peak BF in response to exercise was correlated with power output during SL (r = 0.655, P = 0.002) and DL (r = 0.666, P = 0.001) cycling. The greater exercise performance during SL compared with DL cycling may be partly explained by a greater hyperaemic response when reducing active muscle mass. Despite regular endurance training, older athletes had a lower femoral BF in response to maximal self-paced exercise compared with younger athletes.

Effects of High- Versus Moderate-Intensity Training on Neuroplasticity and Functional Recovery After Focal Ischemia.

BACKGROUND AND PURPOSE: This study was designed to compare the effects of high-intensity interval training (HIT) and moderate-intensity aerobic training (MOD) on functional recovery and cerebral plasticity during the first 2 weeks after cerebral ischemia. METHODS: Rats were randomized as follows: control (n=15), SHAM (n=9), middle cerebral artery occlusion (n=13), middle cerebral artery occlusion at day 1 (n=7), MOD (n=13), and HIT (n=13). Incremental tests were performed at day 1 (D1) and 14 (D14) to identify the running speed associated with the lactate threshold (SLT) and the maximal speed (Smax). Functional tests were performed at D1, D7, and D14. Microglia form, cytokines, p75NTR (pan-neurotrophin receptor p75), potassium-chloride cotransporter type 2, and sodium-potassium-chloride cotransporter type 1 expression were made at D15. RESULTS: HIT was more effective to improve the endurance performance than MOD and induced a fast recovery of the impaired forelimb grip force. The ionized calcium binding adaptor molecule 1 (Iba-1)-positive cells with amoeboid form and the pro- and anti-inflammatory cytokine expression were lower in HIT group, mainly in the ipsilesional hemisphere. A p75NTR overexpression is observed on the ipsilesional side together with a restored sodium-potassium-chloride cotransporter type 1/potassium-chloride cotransporter type 2 ratio on the contralesional side. CONCLUSIONS: Low-volume HIT based on lactate threshold seems to be more effective after cerebral ischemia than work-matched MOD to improve aerobic fitness and grip strength and might promote cerebral plasticity.

Saving mental effort to maintain physical effort: a shift of activity within the prefrontal cortex in anticipation of prolonged exercise.

Executive functioning and attention require mental effort. In line with the resource conservation principle, we hypothesized that mental effort would be saved when individuals expected to exercise for a long period. Twenty-two study participants exercised twice on a cycle ergometer for 10 min at 60% of their maximal aerobic power, with the expectation of exercising for either 10 min or 60 min. Changes in activity in the right dorsolateral prefrontal cortex (rdlPFC) and right medial frontal cortex (rmPFC) were investigated by measuring oxyhemoglobin using near-infrared spectroscopy. Attentional focus and ratings of perceived exertion were assessed at three time points (200, 400, and 600 s). The oxyhemoglobin concentration was lower in the rdlPFC and higher in the rmPFC under the 60-min than under the 10-min condition. Also, attention was less focused in the 60-min than in the 10-min condition. We discuss these results as possible evidence of a disengagement of the brain regions associated with mental effort (executive network), in favor of brain regions linked to resting activity (the default network), in order to save mental resources for the maintenance of exercise.

The differential effects of prolonged exercise upon executive function and cerebral oxygenation.

The acute-exercise effects upon cognitive functions are varied and dependent upon exercise duration and intensity, and the type of cognitive tasks assessed. The hypofrontality hypothesis assumes that prolonged exercise, at physiologically challenging intensities, is detrimental to executive functions due to cerebral perturbations (indicated by reduced prefrontal activity). The present study aimed to test this hypothesis by measuring oxygenation in prefrontal and motor regions using near-infrared spectroscopy during two executive tasks (flanker task and 2-back task) performed while cycling for 60min at a very low intensity and an intensity above the ventilatory threshold. Findings revealed that, compared to very low intensity, physiologically challenging exercise (i) shortened reaction time in the flanker task, (ii) impaired performance in the 2-back task, and (iii) initially increased oxygenation in prefrontal, but not motor regions, which then became stable in both regions over time. Therefore, during prolonged exercise, not only is the intensity of exercise assessed important, but also the nature of the cognitive processes involved in the task. In contrast to the hypofrontality hypothesis, no inverse pattern of oxygenation between prefrontal and motor regions was observed, and prefrontal oxygenation was maintained over time. The present results go against the hypofrontality hypothesis.

Comparison of the influence of age on cycling efficiency and the energy cost of running in well-trained triathletes.

INTRODUCTION: Locomotive efficiency is cited as an important component to endurance performance; however, inconsistent observations of age-related changes in efficiency question its influence in the performance of masters athletes. PURPOSE: This study examined locomotive efficiency in young and masters triathletes during both a run and cycle test. METHODS: Twenty young (28.5 ± 2.6 years) and 20 masters (59.8 ± 1.3 years) triathletes completed an incremental cycling and running test to determine maximal aerobic consumption (VO2max) and the first ventilatory threshold (VT1). Participants then completed 10-min submaximal running and cycling tests at VT1 during which locomotive efficiency was calculated from expired ventilation. Additionally, body fat percentage was determined using skin-fold assessment. RESULTS: During the cycle and run, VO2max was lower in the masters (48.3 ± 5.4 and 49.6 ± 4.8 ml kg(-1) min(-1), respectively) compared with young (61.6 ± 5.7 and 62.4 ± 5.2 ml kg(-1) min(-1), respectively) cohort. Maximal running speed and the cycling power output corresponding to VO2max were also lower in the masters (15.1 ± 0.8 km h(-1) and 318.6 ± 26.0 W) compared with the young (19.5 ± 1.3 km h(-1) and 383.6 ± 35.0 W) cohort. Cycling efficiency was lower (-11.2%) in the masters compared with young cohort. Similar results were observed for the energy cost of running (+10.8%); however, when scaled to lean body mass, changes were more pronounced during the run (+22.1%). CONCLUSIONS: Within trained triathletes, ageing can influence efficiency in both the run and cycle discipline. While disregarded in the past, efficiency should be considered in research examining performance in ageing athletes.

The impact of sleeping with reduced glycogen stores on immunity and sleep in triathletes.

PURPOSE: We investigated the effects of a 3-week dietary periodization on immunity and sleep in triathletes. METHODS: 21 triathletes were divided into two groups with different nutritional guidelines during a 3-week endurance training program including nine twice a day sessions with lowered (SL group) or maintained (CON group) glycogen availability during the overnight recovery period. In addition to performance tests, sleep was monitored every night. Systemic and mucosal immune parameters as well as the incidence of URTI were monitored every week of the training/nutrition protocol. Two-ways ANOVA and effect sizes were used to examine differences in dependent variables between groups at each time point. RESULTS: The SL group significantly improved 10 km running performance (-1 min 13 s, P < 0.01, d = 0.38), whereas no improvement was recorded in the CON group (-2 s, NS). No significant changes in white blood cells counts, plasma cortisol and IL-6 were recorded over the protocol in both groups. The vitamin D status decreased in similar proportions between groups, whereas salivary IgA decreased in the SL group only (P < 0.05, d = 0.23). The incidence of URTI was not altered in both groups. All participants in both groups went to bed earlier during the training program (SL -20 min, CON -27 min, P < 0.05, d = 0.28). In the SL group, only sleep efficiency slightly decreased by 1.1 % (P < 0.05, d = 0.25) and the fragmentation index tended to increase at the end of the protocol (P = 0.06). CONCLUSION: Sleeping and training the next morning regularly with reduced glycogen availability has minimal effects on selected markers of immunity, the incidence of URTI and sleeping patterns in trained athletes.

Pacing strategies during the swim, cycle and run disciplines of sprint, Olympic and half-Ironman triathlons.

PURPOSE: This study investigated the influence of distance on self-selected pacing during the swim, cycle and run disciplines of sprint, Olympic and half-Ironman (HIM) distance triathlon races. METHOD: Eight trained male triathletes performed the three individual races in <2 months. Participants' bikes were fitted with Schoberer Rad Meßtechnik to monitor speed, power output and heart rate during the cycle discipline. Global positioning system was worn to determine speed and heart rate during the swim and run disciplines. RESULT: An even swim pacing strategy was adopted across all distances. A more stochastic pacing was observed during the HIM cycle [standard deviation of exposure variation analysis (EVASD) = 3.21 ± 0.61] when compared with the sprint cycle discipline (EVASD = 3.84 ± 0.44, p = 0.018). Only 20.9 ± 4.1 % of the cycling time was spent more than 10 % above the mean power output in the HIM, compared with 43.8 ± 2.9 % (p = 0.002) and 37.7 ± 11.1 % (p = 0.039) during the sprint and Olympic distance triathlons, respectively. Conversely, 13.6 ± 5.1 % of the cycling time was spent 5-10 % below the mean power output during the HIM, compared with 5.9 ± 1.2 % (p = 0.034) and 8.0 ± 5.1 % (p = 0.045) during the sprint and Olympic distance triathlons, respectively. A negative pacing strategy was adopted during the sprint distance run, compared with positive pacing strategy during the Olympic and HIM. CONCLUSION: Results of this study suggest that pacing strategies during triathlon are highly influenced by distance and discipline, and highlight the importance of developing pacing strategies based on distance, strengths and individual fitness.

Comparison of COSMED'S FitMate™ and K4b2 metabolic systems reliability during graded cycling exercise.

This study compared the reliability of the Cosmed FitMate™ and K4b2 metabolic systems during light to heavy steady state exercise. Expired gas, ventilation were recorded in 50 subjects, using in a random order among four sessions, either the FitMate™ or the Cosmed K4b2. No differences in oxygen consumption were observed between the two systems whatever the intensity. Intraclass correlation were high for both analyzers (respectively for the FitMate™ system and the Cosmed K4b2; ICC: 0.76-0.88 vs. 0.88-0.95). The FitMate™ metabolic system could be a useful reliable and easy-to-use metabolic system in energy expenditure measurement.

Age difference in efficiency of locomotion and maximal power output in well-trained triathletes.

PURPOSE: The aim of this study was to examine the influence of age on cycling efficiency and sprint power output in well-trained endurance masters athletes. METHODS: The investigation was conducted on 60 healthy well-trained triathletes separated into six separate groups (n = 10) depending on age: 20-29 years old; 30-39 years old; 40-49 years old; 50-59 years old; 60-69 years old; 70 years old. Each participant attended the laboratory on three separate occasions to perform (1) an incremental cycling test, (2) maximal peak sprint power test, involving three 5-s sprint efforts (3) and a 10-min sub-maximal cycling test for determination of cycling efficiency. RESULTS: Cycling efficiency decreased beyond 50 years (50-59 years compared with 20-29 years: -7.3 ± 1.8%; p < 0.05) and continued to decrease beyond 60 years (60-69 years compared with 50-59 years: -10.7 ± 2.4%; p < 0.05), no further decrease was observed after 70 years. A continuous impairment in maximal sprint power output was observed after the age of 50 years leading to an overall decrease of 36% between 20-29 years and >70 years. Significant positive relationships were observed between maximal sprint power output and both cycling efficiency (r(2) = 0.64, p < 0.05) and maximal aerobic power (r(2) = 0.42 and p < 0.05). CONCLUSION: The present data indicates a significant effect of ageing on cycling efficiency and maximal sprint power output after 50 years and a significant relationship was found between these two parameters.

Can stereotype threat affect motor performance in the absence of explicit monitoring processes? Evidence using a strength task.

Previous evidence shows that stereotype threat impairs complex motor skills through increased conscious monitoring of task performance. Given that one-step motor skills may not be susceptible to these processes, we examined whether performance on a simple strength task may be reduced under stereotype threat. Forty females and males performed maximum voluntary contractions under stereotypical or nullified-stereotype conditions. Results showed that the velocity of force production within the first milliseconds of the contraction decreased in females when the negative stereotype was induced, whereas maximal force did not change. In males, the stereotype induction only increased maximal force. These findings suggest that stereotype threat may impair motor skills in the absence of explicit monitoring processes, by influencing the planning stage of force production.

Strength training improves cycling efficiency in master endurance athletes.

The purpose of this study was to test the effect of a 3-week strength training program of knee extensor muscles on cycling delta efficiency in master endurance athletes. Nine master (age 51.5 ± 5.5 years) and 8 young (age 25.6 ± 5.9 years) endurance athletes with similar training levels participated in this study. During three consecutive weeks, all the subjects were engaged in a strength training program of the knee extensor muscles. Every week, they performed three training sessions consist of 10 × 10 knee extensions at 70% of maximal repetition with 3 min rest between in a leg extension apparatus. Maximal voluntary contraction torque (MVC torque) and force endurance (End) were assessed before, after every completed week of training, and after the program. Delta efficiency (DE) in cycling was evaluated before and after the training period. Before the training period, MVC torque, End, and DE in cycling were significantly lower in masters than in young. The strength training induced a significant improvement in MVC torque in all the subjects, more pronounced in masters (+17.8% in masters vs. +5.9% in young, P < 0.05). DE in cycling also significantly increased after training in masters, whereas it was only a trend in young. A significant correlation (r = 0.79, P < 0.01) was observed between MVC torque and DE in cycling in masters. The addition of a strength training program for the knee extensor muscles to endurance-only training induced a significant improvement in strength and cycling efficiency in master athletes. This enhancement in muscle performance alleviated all the age-related differences in strength and efficiency.

Age-related changes in cardio-respiratory responses and muscular performance following an Olympic triathlon in well-trained triathletes.

The aim of the present study was to compare the maximal isometric torque and cardio-respiratory parameters in well-trained young and master triathletes prior to and following an Olympic distance triathlon. One day before and 24 h following the event, participants performed three maximum voluntary isometric knee extensions and flexions and an incremental running test on a treadmill to determine the maximal isometric torque, maximal oxygen uptake VO(2max), speed at VO(2max) (vVO(2)max), speed at ventilatory thresholds (VT1 and VT2) and submaximal running economy. Prior to the event VO(2max), vVO(2)max, speed at ventilatory thresholds and running economy were significantly lower in master athletes, but maximal voluntary torque was similar between the groups. 24 h following the race, a similar significant decrease in VO(2max) (-3.1% in masters, and -6.2% in young, p < 0.05), and vVO(2)max (-9.5% in masters, and -5.6% in young, p < 0.05) was observed in both the groups. The speed at VT2 significantly decreased only in master athletes (-8.3%, p < 0.05), while no change was recorded in maximal voluntary torque or submaximal running economy following the event. The results indicate that for well-trained subjects, the overall relative exercise intensity during an Olympic distance triathlon and the fatigue 24 h following the event seem to be independent of age.

Influence of kick frequency on metabolic efficiency and performance at a severe intensity in international monofin-swimmers.

The aim of this study was to examine the effect of kick frequency on metabolic efficiency and performance in elite monofin-swimmers at the surface. Seven participants of international calibre were requested to perform three separate time limit exercises conducted at an intensity corresponding to 97.5% of the velocity at the maximal oxygen uptake. The first Time Limit exercise was systematically conducted at a freely chosen kick frequency (FCK(F)) and the other Time Limit exercises were performed in random order at FCK(F)-10% and FCK(F) + 10%. The slow component of oxygen uptake (VO2sc) was identified independently of the Time Limit exercise (ranging from 180 to 243 ml · min(-1), P < 0.05). No significant change in energy cost of aquatic locomotion (ranging from 565 to (596 J · m(-1)) and [VO2sc) responses was observed between the three Time Limit exercises. An increase or decrease of 10% of the FCK(F) was associated with a significant reduction in Time Limit of -47.3% and -49.1%, respectively (P < 0.05). The analysis of the Time Limit exercise indicates that the selection of kick frequency other than FCK(F) is detrimental to overall monofin-swimming performance. Furthermore, the study results showed that the indicators of metabolic efficiency such as energy cost or [VO2sc) do not determine the performance response in elite monofin-swimmers at a severe intensity.

Endurance exercise immediately before sea diving reduces bubble formation in scuba divers.

Previous studies have observed that a single bout of exercise can reduce the formation of circulating bubbles on decompression but, according to different authors, several hours delay were considered necessary between the end of exercise and the beginning of the dive. The objective of this study was to evaluate the effect of a single bout of exercise taken immediately before a dive on bubble formation. 24 trained divers performed open-sea dives to 30 msw depth for 30 min followed by a 3 min stop at 3 msw, under two conditions: (1) a control dive without exercise before (No-Ex), (2) an experimental condition in which subjects performed an exercise before diving (Ex). In the Ex condition, divers began running on a treadmill for 45 min at a speed corresponding to their own ventilatory threshold 1 h before immersion. Body weight, total body fluid volume, core temperature, and volume of consumed water were measured. Circulating bubbles were graded according to the Spencer scale using a precordial Doppler every 30 min for 90 min after surfacing. A single sub-maximal exercise performed immediately before immersion significantly reduces bubble grades (p < 0.001). This reduction was correlated not only to sweat dehydration, but also to the volume of water drunk at the end of the exercise. Moderate dehydration seems to be beneficial at the start of the dive whereas restoring the hydration balance should be given priority during decompression. This suggests a biphasic effect of the hydration status on bubble formation.

Effects of Ramadan intermittent fasting on middle-distance running performance in well-trained runners.

OBJECTIVE: To assess whether Ramadan intermittent fasting (RIF) affects 5000-m running performance and physiological parameters classically associated with middle-distance performance. DESIGN: Two experimental groups (Ramadan fasting, n = 9, vs control, n = 9) participated in 2 experimental sessions, one before RIF and the other at the last week of fasting. SETTING: For each session, subjects completed 4 tests in the same order: a maximal running test, a maximal voluntary contraction (MVC) of knee extensor, 2 rectangular submaximal exercises on treadmill for 6 minutes at an intensity corresponding to the first ventilatory threshold (VT1), and a running performance test (5000 m). PARTICIPANTS: Eighteen, well-trained, middle-distance runners. MAIN OUTCOME MEASURES: Maximal oxygen consumption, MVC, running performance, running efficiency, submaximal VO(2) kinetics parameters (VO(2), VO(2)b, time constant τ, and amplitude A1) and anthropometric parameters were recorded or calculated. RESULTS: At the end of Ramadan fasting, a decrease in MVC was observed (-3.2%; P < 0.00001; η, 0.80), associated with an increase in the time constant of oxygen kinetics (+51%; P < 0.00007; η, 0.72) and a decrease in performance (-5%; P < 0.0007; η, 0.51). No effect was observed on running efficiency or maximal aerobic power. CONCLUSIONS: These results suggest that Ramadan changes in muscular performance and oxygen kinetics could affect performance during middle-distance events and need to be considered to choose training protocols during RIF.

Physiological and Mechanical Indices Serving the New Cross-Country Olympic Mountain Bike Performance.

OBJECTIVES: To identify relevant physiological, mechanical, and strength indices to improve the evaluation of elite mountain bike riders competing in the current Cross-Country Olympic (XCO) format. METHODS: Considering the evolution of the XCO race format over the last decade, the present testing protocol adopted a battery of complementary laboratory cycling tests: a maximal aerobic consumption, a force-velocity test, and a multi-short-sprint test. A group of 33 elite-level XCO riders completed the entire testing protocol and at least 5 international competitions. RESULTS: Very large correlations were found between the XCO performance and maximal aerobic power output (r = .78; P < .05), power at the second ventilation threshold (r = .83; P < .05), maximal pedaling force (r = .77; P < .05), and maximum power in the sixth sprint (r = .87; P < .05) of the multi-short-sprint test. A multiple regression model revealed that the normalized XCO performance was predicted at 89.2% (F3,29 = 89.507; r = .95; P < .001) by maximum power in the sixth sprint (ß = 0.602; P < .001), maximal pedaling rate (ß = 0.309; P < .001), and relative maximal aerobic power output (ß = 0.329; P < .001). DISCUSSION: Confirming our expectations, the current XCO performance was highly correlated with a series of physiological and mechanical parameters reflecting the high level of acyclic and intermittent solicitation of both aerobic and anaerobic metabolic pathways and the required qualities of maximal force and velocity. CONCLUSION: The combination of physiological, mechanical, and strength characteristics may thus improve the prediction of elite XCO cyclists' performance. It seems of interest to evaluate the ability to repeatedly produce brief intensive efforts with short active recovery periods.

Age-related changes in neuromuscular function and performance following a high-intensity intermittent task in endurance-trained men.

BACKGROUND: Much attention has been focused on the need to design strategies to increase functional capacities in older populations. This has raised several questions regarding the ability of regular endurance training to preserve functional capacity with age. OBJECTIVE: The purpose of this study was to examine the age-associated changes in neuromuscular function in endurance-trained men before and after a high-intensity, intermittent fatiguing task. METHOD: Twenty-six healthy endurance-trained male subjects: 16 older (59-79 years) and 10 young (20-34 years) men performed a high-intensity, intermittent fatiguing exercise corresponding to 10 sets of 10 repetitions on a horizontal leg press at 70% of the individual one-repetition maximum. Maximal voluntary contractions and evoked contractions of the knee extensor muscles were performed before and after the exercise. RESULTS: Decreases in maximum voluntary contractions (older: -9.7%; young: -14.3%) and electromyographic activity were not different between groups. Peak twitch torque was reduced only for the older men and no changes in voluntary activation and M-wave properties were recorded in either group. CONCLUSION: The present study indicates that in endurance-trained men aged 59-79 years, muscle functional capacities are maintained despite losses in strength and contractile function related to the age.