Relationship between maximal oxygen uptake on different ergometers, lean arm volume and strength in paraplegic subjects

The present experiment was designed to study the importance of strength and muscle mass as factors limiting maximal oxygen uptake (V˙O_{2 max} ) in wheelchair subjects. Thirteen paraplegic subjects [mean age 29.8 (8.7) years] were studied during continuous incremental exercises until exhaustion on an arm-cranking ergometer (AC), a wheelchair ergometer (WE) and motor-driven treadmill (TM). Lean arm volume (LAV) was estimated using an anthropometric method based upon the measurement of various circumferences of the arm and forearm. Maximal strength (MVF) was measured while pushing on the rim of the wheelchair for three positions of the hand on the rim (−30°, 0° and +30°). The results indicate that paraplegic subjects reached a similar V˙O_{2 max} [1.23 (0.34) l · min⁻¹, 1.25 (0.38) l · min⁻¹, 1.22 (0.18) l · min⁻¹ for AC, TM and WE, respectively] and V˙O_{2 max} /body mass [19.7 (5.2) ml · min⁻¹ · kg⁻¹, 19.5 (6.14) ml · min⁻¹ · kg⁻¹, 19.18 (4.27) ml · min⁻¹ · kg⁻¹ for AC, TM and WE, respectively on the three ergometers. Maximal heart rate f _{c max} during the last minute of AC (173 (17) beats · min⁻¹], TM [168 (14) beats · min⁻¹], and WE [165 (16) beats · min⁻¹], were correlated, but f _{c max} was significantly higher for AC than for TM (P<0.03). There were significant correlations between MVF and LAV (P<0.001) and between the MVF data obtained at different angles of the hand on the rim [311.9 (90.1) N, 313.2 (81.2) N, 257.1 (71) N, at −30°, 0° and +30°, respectively]. There was no correlation between V˙O_{2 max} and LAV or MVF. The relatively low values of f _{c max} suggest that V˙O_{2 max} was, at least in part, limited by local aerobic factors instead of central cardiovascular factors. On the other hand, the lack of a significant correlation between V˙O_{2 max} and MVF or muscle mass was not in favour of muscle strength being the main factor limiting V˙O_{2 max} in our subjects. Accepted: 31 January 1997     

Maximal oxygen uptake, anaerobic threshold and running economy in women and men with similar performances level in marathons

Sex differences in running economy (gross oxygen cost of running, C_R), maximal oxygen uptake (VO_2max), anaerobic threshold (Th_an), percentage utilization of aerobic power (% VO_2max), and Th_an during running were investigated. There were six men and six women aged 20–30 years with a performance time of 2 h 40 min over the marathon distance. The VO_2max, Th_an, and CR were measured during controlled running on a treadmill at 1° and 3° gradient. From each subject's recorded time of running in the marathon, the average speed (v _M) was calculated and maintained during the treadmill running for 11 min. The VO_{2 max} was inversely related to body mass (m _b), there were no sex differences, and the mean values of the reduced exponent were 0.65 for women and 0.81 for men. These results indicate that for running the unit ml·kg^–0.75·min^–1 is convenient when comparing individuals with different m _b. The VO_2max was about 10% (23 ml·kg^–0.75·min^–1) higher in the men than in the women. The women had on the average 10–12 ml·kg^–0.75·min^–1 lower VO₂ than the men when running at comparable velocities. Disregarding sex, the mean value of C_R was 0.211 (SEM 0.005) ml·kg^–1·m^–1 (resting included), and was independent of treadmill speed. No sex differences in Th_an expressed as % VO_2max or percentage maximal heart rate were found, but Than expressed as VO₂ in ml·kg^–0.75·min^–1 was significantly higher in the men compared to the women. The percentage utilization of f _emax and concentration of blood lactate at v _M was higher for the female runners. The women ran 2 days more each week than the men over the first 4 months during the half year preceding the marathon race. It was concluded that the higher VO_2max and Th_an in the men was compensated for by more running, superior C_R, and a higher exercise intensity during the race in the performance-matched female marathon runners.     

Simultaneous potentiation and fatigue in quadriceps after a 60-second maximal voluntary isometric contraction

Potential mechanisms of fatigue (metabolic factors) and potentiation (phosphate incorporation by myosin phosphorylatable light chains) were investigated during recovery from a 60-s maximal voluntary isometric contraction (MVC) in the quadriceps muscle of 12 subjects. On separate days before and for 2 h after the 60-s MVC, either a 1-s MVC or electrically stimulated contractions were used as indexes to test muscle performance. Torque at the end of the 60-s MVC was 57% of the initial level, whereas torques from a 1-s MVC and 50-Hz stimulation were most depressed in the immediate recovery period. At this time, muscle biopsy analyses revealed significant decreases in ATP and phosphocreatine and a 19-fold increase in muscle lactate. Conversely, isometric twitch torque and torque from a 10-Hz stimulus were the least depressed of six contractile indexes and demonstrated potentiation of 25 and 34%, respectively, by 4 min of recovery (P less than 0.05). At this time, muscle lactate concentration was still 16 times greater than at rest. An increased phosphate content of the myosin phosphorylatable light chains (P less than 0.05) was also evident both immediately and 4 min after the 60-s MVC. We conclude that the 60-s MVC produced marked force decreases likely due to metabolic displacement, while the limited decline in the twitch and 10-Hz torques and their significant potentiation suggested that myosin phosphorylation may provide a mechanism to enhance contractile force under conditions of submaximal activation during fatigue.     

EMG power spectra of trunk muscles during graded maximal voluntary isometric contraction in flexion-rotation and extension-rotation

The purpose of this study was to determine the electromyographic (EMG) power spectral characteristics of seven trunk muscles bilaterally during two complex isometric activities extension-rotation and flexion-rotation, in both genders to describe the frequency-domain parameters. Eighteen normal young subjects volunteered for the study. The subjects performed steadily increasing isometric extension-rotation and flexion-rotation contractions in a standard trunk posture (40 degrees flexed and 40 degrees rotated to the right). A surface EMG was recorded from the external and internal oblique, rectus abdominis, pectoralis, latissimus dorsi, and erector spinae muscles at the 10th thoracic and the 3rd lumbar vertebral levels, at 1 kHz and 25%, 50%, 75% and 100% of maximal voluntary contraction (MVC). The median frequency (MF), mean power frequency (MPF), frequency spread and peak power were obtained from fast Fourier transform analysis. The MF and MPF for both extension-rotation and flexion-rotation increased with the grade of contraction for both males and females. The EMG spectra in flexion-rotation were different from those of extension-rotation (P < 0.001). The left external and right internal oblique muscles played the role of antagonists in trunk extension-rotation. There was an increase in the MF of the trunk muscles with increasing magnitude of contraction. Frequency-domain parameters for both the male and female subjects were significantly different (P < 0.001).     

Repeatability of maximal voluntary force and of surface EMG variables during voluntary isometric contraction of quadriceps muscles in healthy subjects

The repeatability of initial values and rate of change of EMG signal mean spectral frequency (MNF), average rectified values (ARV), muscle fiber conduction velocity (CV) and maximal voluntary contraction (MVC) was investigated in the vastus medialis obliquus (VMO) and vastus lateralis (VL) muscles of both legs of nine healthy male subjects during voluntary, isometric contractions sustained for 50 s at 50% MVC. The values of MVC were recorded for both legs three times on each day and for three subsequent days, while the EMG signals have been recorded twice a day for three subsequent days. The degree of repeatability was investigated using the Fisher test based upon the ANalysis Of VAriance (ANOVA), the Standard Error of the Mean (SEM) and the Intraclass Correlation Coefficient (ICC).

Data collected showed a high level of repeatability of MVC measurement (normalized SEM from 1.1% to 6.4% of the mean). MNF and ARV initial values also showed a high level of repeatability (ICC>70% for all muscles and legs except right VMO). At 50% MVC level no relevant pattern of fatigue was observed for the VMO and VL muscles, suggesting that other portions of the quadriceps might have contributed to the generated effort. These observations seem to suggest that in the investigation of muscles belonging to a multi-muscular group at submaximal level, the more selective electrically elicited contractions should be preferred to voluntary contractions.     

Effects of age and sex on fatigability and recovery from a sustained maximal isometric voluntary contraction

The aim was to assess the effects of sex and age on fatigability and recovery from sustained maximal voluntary contraction (MVC) of the knee extensor muscles. The central (central activation ratio (CAR) and electrical activity amplitude) and peripheral (electrically evoked torque and muscle contractile properties) factors contributing to fatigue and recovery of 24 young adults (12 males) aged 23.2 ± 3.6 years and 20 older adults (12 males) aged 70.6 ± 4.4 years were compared. The increase in central and peripheral fatigue was greater (p ⩽ 0.01) in the young adults vs the older adults. Sex differences (p = 0.002) regarding MVC were attributed to the greater (p < 0.01) peripheral fatigue of males vs females. The recovery rate of MVC was greater (p < 0.001) in the young adults vs the older adults, with no sex effect. The recovery of MVC was correlated with the CAR in older adults (p = 0.001). Thus, the greater endurance observed with age is caused by differences in central and peripheral mechanisms, whereas the greater endurance in females is caused by a difference in a mechanism located within the muscle. The impaired recovery from fatigue in older adults relied more on the recovery of central factors.     

Maximal oxygen uptake, anthropometry and physical activity in a randomly selected sample of 8 and 13 year old children in Sweden

Maximal oxygen uptake was assessed in 101 randomly selected 8 and 13 year old children. In both age groups a significantly higher aerobic capacity was found in boys than in girls, both in absolute terms and when maximal oxygen uptake was related to body weight, lean body mass and lean leg volume. Among girls, maximal oxygen uptake per kg body weight was lower in the older than in the younger (p less than 0.05). Estimation of spontaneous physical activity, by means of a questionnaire and the actometry method, indicated that physical activity was greater in children with a high than in those with a low aerobic capacity.     

Maximal mechanical power output and capacity of cyclists and young adults

The maximal average power output (Wmax) has been examined in 10 male students, 22 pursuit and 12 sprint cyclists. In 24 of these subjects (8 students, 10 pursuit and 6 sprint cyclists), estimates of the maximal capacity (Wcap) of the short-term anaerobic energy yielding processes were made. The results show that the sprinters had a higher absolute Wmax (1241 +/- 266 W) and Wcap (16.7 +/- 4.9 kJ) than either the students (1019 +/- 183 W, 14.7 +/- 2.8 kJ) or the pursuit cyclists (962 +/- 206 W, 14.0 +/- 2.9 kJ). However, the differences were removed when the values were standardised for muscle size. In the sprinters the Wmax was attained at an optimal pedal frequency Vopt of 132 +/- 3 min-1 and the estimated maximal velocity of pedalling (V0) was 262 +/- 8 min-1. The comparable figures in the students and pursuit cyclists were 118 +/- 8 min-1, 235 +/- 17 min-1 and 122 +/- 6 min-1, 242 +/- 12 min-1 respectively. The coefficient of variation of duplicate measurements of Wcap was found to be +/- 9%. Using data of Wilkie (1968) for muscle phosphagen and glycolytic stores (27 mmol.kg-1), it was estimated that the probable efficiency of the anaerobic processes during maximal cycling was 0.22. It was concluded that Wmax and Wcap are largely determined by body size and muscularity. The efficiency of anaerobiosis appears to be of the same order of magnitude as found for oxidative work.     

Non-uniform mechanical activity of quadriceps muscle during fatigue by repeated maximal voluntary contraction in humans

To determine the non-uniform surface mechanical activity of human quadriceps muscle during fatiguing activity, surface mechanomyogram (MMG), or muscle sound, and surface electromyogram (EMG) were recorded from the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) muscles of seven subjects during unilateral isometric knee extension exercise. Time- and frequency-domain analyses of MMG and of EMG fatigued by 50 repeated maximal voluntary contractions (MVC) for 3 s, with 3-s relaxation in between, were compared among the muscles. The mean MVC force fell to 49.5 (SEM 2.0)% at the end of the repeated MVC. Integrated EMG decreased in a similar manner in each muscle head, but a marked non-uniformity was found for the decline in integrated MMG (iMMG). The fall in iMMG was most prominent for RF, followed by VM and VL. Moreover, the median frequency of MMG and the relative decrease in that of EMG in RF were significantly greater (P < 0.05) than those recorded for VL and VM. These results would suggest a divergence of mechanical activity within the quadriceps muscle during fatiguing activity by repeated MVC. Accepted: 19 January 1999     

The prediction of maximal oxygen uptake before and after physical training in children.

Maximal oxygen consumption (V O2 max) expressed in ml/kg/min and predicted V O2 max were determined before and after 8 weeks of training in 24 boys 10-12 years. Training involved 13 of them while 11 were controls. Predicted V O2 max was based on submaximal cycling heart rate according to the Astrand-Rhyming procedure. Pre-training, V O2 max was underpredicted by 12 per cent. This resulted mainly from an apparently low cycling efficiency in these subjects compared to that implicit in the prediction equation. Although adjustments in the prediction equation could equalize the means for V O2 max and predicted V O2 max, the rather low correlation (r = .55) between these measures precluded the accurate prediction of individual scores. V O2 max remained unchanged with training while submaximal heart rate during bicycle and treadmill exercise showed a significant decrease, resulting in predicted increases in V O2 max in children. Since V O2 max was actually unchanged, the prediction falsely indicated an improvement. Furthermore, despite a significantly lower heart rate in the trained group, there was no difference in predicted V O2 max between the groups post-training. These findings indicate that if V O2 max is the parameter of interest, it would seem to be more satisfactory to measure it directly until more reliable methods of prediction are developed.     

Peak power output predicts maximal oxygen uptake and performance time in trained cyclists

The purposes of this study were firstly to determine the relationship between the peak power output (Wpeak) and maximal oxygen uptake (VO2max) attained during a laboratory cycling test to exhaustion, and secondly to assess the relationship between Wpeak and times in a 20-km cycling trial. One hundred trained cyclists (54 men, 46 women) participated in the first part of this investigation. Each cyclist performed a minimum of one maximal test during which Wmax and VO2max were determined. For the second part of the study 19 cyclists completed a maximal test for the determination of Wpeak, and also a 20-km cycling time trial. Highly significant relationships were obtained between Wpeak and VO2max (r = 0.97, P less than 0.0001) and between Wpeak and 20-km cycle time (r = -0.91, P less than 0.001). Thus, Wpeak explained 94% of the variance in measured VO2max and 82% of the variability in cycle time over 20 km. We concluded that for trained cyclists, the VO2max can be accurately predicted from Wpeak, and that Wpeak is a valid predictor of 20-km cycle time.     

Effects of basketball training on maximal oxygen uptake, muscle strength, and joint mobility in young basketball players

The purpose of this study was to examine the effects of prolonged basketball skills training on maximal aerobic power, isokinetic strength, joint mobility, and body fat percentage, in young basketball players, and controls of the same age. Twenty basketball players and 18 control boys participated in the study. Basketball players participated both in their school's physical education program and in a children's basketball team training program. Controls participated only in their school's physical education program. All subjects were tested every 6 months (18 months total, 11(1/2), 12, 12(1/2), 13 years old) for VO(2)max, peak torque values of the quadriceps and hamstrings at 180 and 300 degrees x s(-1) and range of motion of the knee and hip joints. Body fat percentage was assessed at the beginning and the end of the experimental period. Results showed that the basketball group had lower heart rate values in all ages and higher VO(2) values in the initial test compared with the control in submaximal intensity. The VO(2)max was altered in both groups on the final test, when compared to the initial test. However, the basketball group had a higher VO(2)max on each of the 6-month follow-up measurements, compared to the control group (p < 0.001). At the end of the 18-month follow-up period no significant differences were observed in isokinetic strength and joint mobility of the lower limbs between the 2 groups. On the contrary, the boys of the trained group had significantly lower percentage body fat values, compared to controls. In conclusion, regular basketball training increased aerobic power and decreased body fat percentage of prepubescent boys, while it did not affect muscle strength and joint mobility of the lower limbs. The major implication suggested by the findings of the present study is that, in order to improve the basic physical components, specific training procedures should be incorporated during the basketball training sessions. It is recommended that all children should be involved in some type of cardiovascular and resistance training program.     

Maximal oxygen uptake,sweating and tolerance to exercise in the heat

The purpose of this experiment was to determine if tolerance to exercise in the heat is related to maximal oxygen uptake (max ₀₂) and sweating. Seven men with max ₀₂ between 42 and 66 ml/(min·kg) underwent one 2-hr exposure at 24°C T_q while working on a bicycle ergometer at rel ₀₂ of 28% ( ₀₂ = 1.23 1/min). In the hot exposures the high capacity subjects had maximal sweat rates of 800 to 1,000 g/(hr·m²) while the lower capacity men sweated 300 to 400 g/(hr·m²). These differences in sweating were not related to neuromuscular stimuli, ₀₂ (metabolic rate), T_re, T_re, _s, _s or tolerance time. Tolerance to exercise in the heat was not related to maximal ₀₂ capacity when the subjects worked at the same relative load in spite of large differences in sweating. These results question the importance of the rate of sweating for predicting work performance in hot environments.

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Zusammenfassung Das Ziel dieser Untersuchung war, zu prüfen, ob die Toleranz bei Arbeit in der Hitze in einer Beziehung steht zur maximalen O₂-Aufnahme und Schwitzen. Sieben Männer mit V₀₂ zwischen 42 – 66 ml/(min·kg) wurden belastet während 2 Stunden bei T_a 24°C und 3 × 2 Stunden bei 47°C mit Arbeit auf dem Fahrrad-Ergometer bei im Mittel von 28% V₀₂ = 1.23 1/min. Während der Hitzebelastung zeigten die leistungsfähigen Personen Schweissekretionsraten von 800 – 1000 g/(hr·m²) und die wenig leistungsfähigen 300 – 400 g/(hr·m²). Diese Unterschiede waren ohne Beziehung zu neuromuskulären Stimuli, Stoffwechselrate, T_re, T_re, _s, _s oder der Toleranzzeit. Ausdauer bei Arbeit in der Hitze war ohne Beziehung zur maximalen V₀₂-Kapazität, wenn die Personen bei der gleichen relativen Belastung arbeiteten tro grosser Unterschiede im Schwitzen. Die Ergebnisse stellen den Wert der Schweissekretionsrate zur Voraussage der Arbeitsleistung in der Hitze in Frage.

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Resume Dans cette étude, on a cherché à voir si la tolérance au travail sous contrainte de chaleur était en relation avec la possibilité maximum d'absorption de O₂ ( ₀₂) d'une part, de transpirer d'autre part. 7 hommes présentant des ₀₂ compris entre 42 et 66 ml/(min · kg) ont pédalé sur un ergomètre pendant 2 heures par une T_a de 24°C et 3 × 2 heures par 47°C et cela par une ₀₂ relative de 28% ( ₀₂ = 1,25 1/min). Durant l'effort sous contrainte de chaleur, les plus actifs ont eu des sécrétions de sueur de 800 à 1.000 g h^–1 m^–2 et les moins actifs de 300 à 400 g/h · m². Ces différences étaient sans rapport avec les stimulus neuro-musculaires, le taux de métabolisme, T_re, T_re, T_s et T_s ou la durée de tolérance. L'endurance au travail sous contrainte de chaleur n'a pas été fonction de la capacité maximum de ₀₂, lorsque les personnes travaillaient dans des conditions analogues, même si l'on a noté de grandes différences dans la transpiration. Ces résultats mettent en doute la représentativité du taux de sécrétion de sueur comme indicatif des possibilités de travailler en atmosphère chaude.

     

Effects of prolonged cycle ergometer exercise on maximal muscle power and oxygen uptake in humans

The mechanical power (W_tot, W·kg^–1) developed during ten revolutions of all-out periods of cycle ergometer exercise (4–9 s) was measured every 5–6 min in six subjects from rest or from a baseline of constant aerobic exercise [50%–80% of maximal oxygen uptake (VO_2max)] of 20–40 min duration. The oxygen uptake [VO₂ (W·kg^–1, 1 ml O₂ = 20.9 J)] and venous blood lactate concentration ([la]_b, mM) were also measured every 15 s and 2 min, respectively. During the first all-out period, W_tot decreased linearly with the intensity of the priming exercise (W_tot = 11.9–0.25·VO₂). After the first all-out period (i greater than 5–6 min), and if the exercise intensity was less than 60% VO_2max, W_tot, VO₂ and [la]_b remained constant until the end of the exercise. For exercise intensities greater than 60% VO_2max, VO₂ and [la]_b showed continuous upward drifts and W_tot continued decreasing. Under these conditions, the rate of decrease of W_tot was linearly related to the rate of increase of V [(d W_tot/dt) (W·kg^–1·s^–1) = 5.0·10^–5 –0.20·(d VO₂/dt) (W·kg^–1·s^–1)] and this was linearly related to the rate of increase of [la]_b [(d VO₂/dt) (W·kg^–1·s^–1) = 2.310^–4 + 5.910^–5·(d [la]_b/dt) (mM·s^–1)]. These findings would suggest that the decrease of W_tot during the first all-out period was due to the decay of phosphocreatine concentration in the exercising muscles occurring at the onset of exercise and the slow drifts of VO₂ (upwards) and of W_tot (downwards) during intense exercise at constant W_tot could be attributed to the continuous accumulation of lactate in the blood (and in the working muscles).     

The influence of contraction type,prior performance of a maximal voluntary contraction and measurement duration on fine-wire EMG amplitude

We aimed to investigate the impact of time on fine-wire (fw) electromyography (EMG) signal amplitude, and to determine whether any attenuation is confounded by task type. Twenty healthy participants were instrumented with fw and surface (s) EMG electrodes at the biceps brachii bilaterally. Participants held a weight statically with one arm and with the other arm either repeated the same task following a maximum voluntary contraction (MVC) or repeated dynamic elbow flexion/extension contractions. Each task was repeated for 30 s every five minutes over two hours. EMG amplitude was smoothed and normalized to time = 0. Stable median power frequency of the s-EMG ruled out the confounding influence of fatigue. Repeated-measures ANCOVAs determined the effect of electrode type and time (covariate) on EMG amplitude and the confounding impact of task type. During the isometric protocol, fw-EMG amplitude reduced over time (p = 0.002), while s-EMG amplitude (p = 0.895) and MPF (p > 0.05) did not change. Fw-EMG amplitude attenuated faster during the dynamic than the isometric protocol (p = 0.008) and there was evidence that the MVC preceding the isometric protocol impacted the rate of decline (p = 0.001). We conclude that systematic signal attenuation of fw-EMG occurs over time and is more pronounced during dynamic tasks.     

The relationship between maximal oxygen uptake and glucose tolerance/insulin response ratio in normal young men.

Maximal oxygen uptake (VO2max.), glucose tolerance (K-value), and insulin response (IRI-area) were studied in seventeen young, non-obese, non-diabetic males. The ratio between K-value and IRI-area correlated significantly with VO2 max. (r = 0.70, p less than 0.01) also when differences in body fat mass were eliminated by partial correlation analysis (r = 0.56, p less than 0.05). Subjects with a high VO2 max. thus maintained a given glucose tolerance with a lower insulin response than did subjects in whom VO2 max. was low.     

Anaerobic threshold and maximal steady-state blood lactate in prepubertal boys

To elucidate further the special nature of anaerobic threshold in children, 11 boys, mean age 12.1 years (range 11.4-12.5 years), were investigated during treadmill running. Oxygen uptake, including maximal oxygen uptake (VO2max), ventilation and the "ventilatory anaerobic threshold" were determined during incremental exercise, with determination of maximal blood lactate following exercise. Within 2 weeks following this test four runs of 16-min duration were performed at a constant speed, starting with a speed corresponding to about 75% of VO2max and increasing it during the next run by 0.5 or 1.0 km.h-1 according to the blood lactate concentrations in the previous run, in order to determine maximal steady-state blood lactate concentration. Blood lactate was determined at the end of every 4-min period. "Anaerobic threshold" was calculated from the increase in concentration of blood lactate obtained at the end of the runs at constant speed. The mean maximal steady-state blood lactate concentration was 5.0 mmol.l-1 corresponding to 88% of the aerobic power, whereas the mean value of the conventional "anaerobic threshold" was only 2.6 mmol.l-1, which corresponded to 78% of the VO2max. The correlations between the parameters of "anaerobic threshold", "ventilatory anaerobic threshold" and maximal steady-state blood lactate were only poor. Our results demonstrated that, in the children tested, the point at which a steeper increase in lactate concentrations during progressive work occurred did not correspond to the true anaerobic threshold, i.e. the exercise intensity above which a continuous increase in lactate concentration occurs at a constant exercise intensity.     

Electrically evoked and voluntary maximal isometric tension in relation to dynamic muscle performance in elderly male subjects, aged 69 years

The dynamic performance and electrically evoked mechanical properties of elderly triceps surae muscle have been investigated in 9 men, aged 69 yr. Dynamic performance consisted of cycling on a force bicycle and a vertical jump off two feet from a force platform. The results showed that the time to peak tension (TPT) and half relaxation time (1/2 RT) were significantly greater (p less than 0.001) by 30 ms and 22 ms and the supramaximal twitch (Pt) and tetanic (20 Hz-P020) tensions and maximal voluntary contraction (MVC) were less by 45 N (-33%), 708 N (-49%), and 899 N (-43%) in the elderly compared with young male control subjects. On the force platform, the height jumped (Ht), maximal force exerted (P), take-off velocity (VT), net impulse (NI) and peak power output (W) were less by 18.6 cm, 173 N, 0.9 ms-1, 52 Ns and 1120 w respectively. Similar differences of power, force and velocity were observed on the force bicycle. The reduction of W in the elderly was associated with the contractile characteristics of the leg muscle. The loss of contractile speed and capacity to to generate force in old people was reflected in their inability to develop power during the performance of a maximal vertical jump and cycling.