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Background The 30-s-long Wingate Anaerobic Test (WAnT_30s) has some limitations in high-level athletes. A shorter version might be helpful for both clinical applications and performance assessment. The comparison between the traditional WAnT_30s and a shorter version has never been carried out yet in Paralympic athletes. Aim To assess if a 10-s-long Wingate Anaerobic Test (WAnT_10s) could be used to accurately assess and predict the anaerobic components of physical fitness as an alternative to the traditional WAnT_30s in male Paralympic athletes. Methods Forty-four trained male Paralympic Athletes grouped by severity of locomotor impairment completed the WAnT_30s and the WAnT_10s with an arm cranking ergometer. Differences between mean and peak power achieved throughout both WAnTs were analysed using a mixed-design analysis of variance and predictivity was assessed by stepwise linear regression analysis. Results In the whole sample, peak power values were similar (P > 0.005) in the two tests and the WAnT_10s mean power was significantly higher than that in the WAnT_30s (P R2 = 0.906; P Conclusion The WAnT_10s is accurate to assess peak power, is definitively appropriate to evaluate the alactic anaerobic metabolism and seems able to predict the mean power as traditionally evaluated through a WAnT_30s in male Paralympic Athletes. Thus, it can be used to assess the anaerobic components of physical fitness in this athletic population.

In the present study the influence of speed of contraction on the interplay between recruitment and firing rate of motor units (MUs) was assessed. The surface electromyographic (sEMG) signal was recorded in nine healthy subjects from the right biceps brachii using a linear electrode array during ramp isometric contractions (from 0 to 100% of the maximal voluntary force, MVC) at 5, 10, and 20% MVC s(-1) (ramp phase), followed by 10 s of sustained MVC (hold phase). The median frequency (MDF), Root Mean Square (RMS) and conduction velocity (CV) of sEMG, were computed on adjacent epochs covering a force range of 5% MVC each. Full motor unit recruitment (FMUR) point was assessed as the force level at which MDF reached its maximum value; the MDF decay during the hold phase was taken as an index of localized muscle fatigue. At 5% MVC s(-1), FMUR was reached at 52.3% MVC. At 10%MVC s(-1) FMUR was achieved at 58% MVC; while at 20% MVC s(-1) FMUR point was located at 77% MVC, being statistically different from 5 and 10% MVCs(-1) ramps (p

The aim of this study was to evaluate the influence of exposure to altitude on muscle endurance during isometric contractions. Six sedentary subjects were studied. Surface electromyograph (sEMG) activity was recorded from the right biceps brachii (BB) during exhausting isometric exercise at 80% maximal voluntary contraction. Experiments were performed before, during and 6 months after a 12 day stay at the EV-K2 laboratory (Nepal, 5,050 m above sea level). From the sEMG signals from BB, the median frequencies (fmed) were computed for consecutive 1 s epochs. The sEMG was also analysed using a non-linear tool, the recurrence quantification analysis, and the percentage of determinism (%DET) was then calculated. The haemoglobin saturation significantly decreased at altitude. The mean (SD) BB endurance time decreased from 22.4 (4) s to 18.3 (4.7) s (P < 0.05). After exposure to altitude a significant variation in fmed and %DET slopes was observed. We concluded that during the first period of acclimatisation at altitude there was an impairment of isometric muscle endurance performance and there was also evidence of a modified myoelectric activity pattern suggesting a greater fatigability of the neuromuscular system.

Objective: This research aims to: a) assess the energy expenditure during typical forestry activities; b) assess the actual workload of forestry work; c) define the eventual relationship between oxygen uptake ( ) and heart rate during the studied working phases.Methods: Eleven healthy skilled forestry workers were studied. Using a portable device, oxygen uptake ( ), carbon dioxide output ( ), pulmonary ventilation ( ) and heart rate (HR) were measured. The forestry work was divided into four phases: walking uphill, felling, limbing & chain-sawing and complementary activities. A work time report was kept and in each phase a weighted average (WA) of all parameters was obtained.Results:Walking uphill, felling, limbing & chain-sawing activities did not show significant statistical differences between each other and were classified as heavy activities (mean 2.17 lmin-1,mean HR 157 beatmin-1). The complementary activity was found to be less demanding and statistically differed in respect to the others ( 0.55 l min-1, HR 98 beat min-1). By theWA, the actual workload of forestry work resulted in a moderate to heavyoptimal job ( and HR being 1.51 l min-1 and 133.5 beat min-1 respectively in a typical working day). Furthermore it was possible to set up a relationship between and HR for the forestry work.Conclusions: Forestry activity can be classified as moderate to heavy-optimal. Finally, a good and linear correlation between and HR proved to be an easy tool to evaluate the metabolic demand.

In some types of human and animal locomotion, speed influences the amount of metabolic energy expended per unit mass and distance (energy cost, EC) and as speed decreases or increases away from a healthy person’s self-selected speed (SSS), the EC increases. When asked to climb a vertical wall using their preferred speed, similar to walking, climbers with the same level of skill spontaneously select comparable speeds. The present research was designed to investigate how speed of ascent affects the EC of climbing; we were also interested in finding out whether climbers with the same level of skill exhibit a common SSS and if it is correlated with optimal economy (i.e. minimum EC). A representative experimental set-up was prepared to quantify the economy of rock climbing by measuring steady-state oxygen intake (VO2) in very skilled climbers while climbing at their SSS and at higher (HS) and lower (LS) speed, and computing the relative EC. The main findings were: (a) climbers with the same level of skill exhibited the same preferred climbing speed (10.2 ± 1.5 m·min−1) at the same fraction of their maximum VO2 (VO2peak) measured on a cycle ergometer (71.7 ± 15.2%), and (b) climbing economy continuously increased as speed increased from LS to HS. Thus climbing at the SSS does not correspond to the optimal economy. A possible explanation for these findings may be that although it does not match the minimum EC, the SSS would be the best compromise between the need to reduce the time spent in isometric work (useless and costly) and the need to avoid early muscle fatigue due to increased speed and frequency of muscle contraction.

The purpose of this study is to estimate the energy cost of ski mountaineering at different speeds under laboratory conditions.By using roller skis on a motorized treadmill we have estimated the energy cost and biomechanics parameters of ski mountaineering as a function of climbing speed at the gradient of 21%.The metabolic energy spent for unit mass and distance, C, shows a broad minimum of about 10.6±0.2 J kg-1m-1 at roughly 3.5 km h-1. In addition we find a size-dependent effect: tall subjects spend less metabolic energy for unit mass and distance than small subjects at the same speed.The value of C measured in laboratory agrees with that obtained in the field at the preferred speed. This shows that skiers self select a speed that minimizes their metabolic cost. The dependence of C on the subject's size is explained by a simple model of the skier's dynamics. In addition we have calculated the ratio between mechanical work and metabolic energy, which may give some hints on the efficiency as a function of the speed. It turns out that efficiency increases with the speed up to a maximum located at around 4.5 km/h.

The present investigation aimed to establish whether noncompetitive rock climbing fulfills sports medicine recommendations for maintaining a good level of aerobic fitness. The physiological profile of 13 rock climbers, 8 men (age, 43 ± 8 years) and 5 women (age, 31 -!- 8 years) was assessed by means of laboratory tests. Maximal aerobic power (Vo2peak) and ventilatory threshold (VT) were assessed using a cycloergometer incremental test. During outdoor rock face climbing, Vo2 and heart rate (HR) were measured with a portable metabolimeter and the relative steady-state values (Vo2 and HR during rock climbing) were computed. Blood lactate was measured during recovery. All data are presented as mean ± SD. Vo2peak was 39.1 ± 4.3 mL?kg-'?min ' in men and 39.7 ± 5 mL kg-' ?min_' in women, while VT was 29.4 ± 3.0 mL?kg-'?min ' in men and 28.8 ± 4.6 mL?kg-'?min in women. The Vol during rock climbing was 28.3 ± 1.5 mL?kg-'?min-1 in men and 27.5 ± 3.7 mL kg 'min' in women. The HR during rock climbing was 144 ± 16 b?min-' in men and 164 ± 13 b?min' in women. The aerobic profile was classified from excellent to superior in accordance with the standards of the American College of Sports Medicine (AGSM). The exercise intensity (Vo2 during rock climbing expressed as a percentage of Vo2peak) was 70 ± 6% in men and 72 ± 8% in women. Moreover, the energy expenditure was 1000-1500 kcal per week. In conclusion, noncompetitive rock climbing has proved to be a typical aerobic activity. The intensity of exercise is comparable to that recommended by the American College of Sports Medicine to maintain good cardiorespiratory fitness.

The aim of this study was to assess maximal cardiac and metabolic demand imposed by in place shallow water running (SWR) and to compare such responses with those obtained during treadmill running (TMR).Twelve males, 6 trained (T) pentathletes (age: 19+/-1 years) and 6 untrained (UT) controls (age: 22+/-1 years), performed one maximal TMR test and one SWR maximal test. Heart rate (HR) and oxygen consumption (VO(2)) were continuously measured in both test conditions.In both groups, resting HR decreased immediately after water immersion (UT group: from 81.8+/-6.2 b x min(-1) to 69.2+/-6 b min(-1); T group: from 71.7+/-2.1 b x min(-1) to 61.7+/-7.7 b x min(-1)). In UT subjects SWR metabolic demand was comparable to that obtained during treadmill (VO(2tmr)=47.9 ml min(-1)+/-3.6; VO(2tmr)=45.2 ml x min(-1) +/- 6.8). In contrast, during shallow SWR, T subjects obtained lower V.O(2max) values with respect to TMR (V.O(2tmr)=68.9 mL x min(-1) +/-5.1; VO(2TMR)=57.2 mL x min(-1)+/-3.9; P0.05). In the T group maximal HR was lower during SWR (from 191+/-8.1 to 177+/-7.1). At a given stride frequency, SWR was less demanding than treadmill in terms of V.O(2) and HR responses. During SWR the metabolic adjustments were depressed more than the cardiac adjustments.These findings suggest that in place SWR may be a useful exercise to reduce the effects of detraining.

The aim of the present study was to ascertain if in six young (23–35 years) and in six older (70–72 years) healthy men matched for comparable absolute and specific maximal force of the dominant elbow flexors, differences in isometric endurance, myoelectrical fatigability, and shortening velocity are still recognizable. To assess the specific force, the muscle cross sectional area (CSA) was determined from magnetic resonance imaging (MRI) scans. The performance of the elbow flexors was studied by assessing the isometric endurance times (ET) at different percentages of maximal isometric contraction (MVC), the average muscle fibre conduction velocity of action potentials (CV), and the median frequency (MDF) of the surface electromyogram (sEMG) of the biceps brachii. Finally, the torque-velocity curve was assessed by means of maximal isokinetic contractions at six fixed angular velocities. All data were expressed as the mean (SD). The results showed that: (1) the ET was longer in the older subjects at the highest levels of isometric contraction, independently from the absolute force; (2) the modifications of muscle fibre CV during isometric effort progressed less rapidly in the older than the younger groups, as did those of MDF; and (3) at the same angular velocity, the older subjects exerted less absolute force than the younger subjects. These results suggest an impairment of the neuromuscular system of older men, which is less powerful and less fatigable than that of young men.

Among the healthy elderly, sit-to-stand (STS) movement largely depends on: (a) trunk bending momentum, (b) centre of gravity (CG) position before the body rises and (c) lower limb extensor muscle strength. Because determining whether (c) improvement would affect STS capability in the motor impaired elderly (MIE) has been recommended, we studied the relative importance of (a), (b) and (c) in determining a successful fast STS movement comparing the healthy elderly with MIE with orthopaedic disorders studied before and after a rehabilitation program. Force platform was used to measure body’s posture and kinematics during a STS test and therefore to assess (a), (b) and maximum vertical velocity (VVpeak), assumed as outcome measurement. Knee extensor maximal isometric voluntary contraction normalized by body mass (nMVC) was an indicator of (c). A multiple regression model was built to predict VVpeak from the three determinants of STS movement. In both groups, the model significantly determined VVpeak, with (a) and (c) being significant predictors of VVpeak and (a) being the major predictor. Rehabilitation was effective in improving nMVC. This process resulted in a change of the relative importance of (a) and (c), strength becoming the major predictor of VVpeak. In conclusion the present study demonstrates that a rehabilitative intervention aimed at increasing strength is effective in improving STS capability in MIE.  2003 Elsevier Ltd. All rights reserved.

The present research was aimed at investigating the peculiarities of surface electromyogram (sEMG) signals in 12 weightlifting athletes (WLA) and 9 control subjects (control group, CG) The sEMG signals were recorded from both vastus lateralis muscles during 20 s isometric contractions made at 30% and 60% of the maximal voluntary contraction (MVC). Ground reaction force (vertical component) was recorded using a force plate. The sEMG was analysed in the frequency domain and the median frequency (MDF) was computed over successive 1 s epochs. A non-linear technique, recurrence quantification analysis was also applied to assess the presence and time course of deterministic structures in sEMG. The percentage of determinism (%DET) was used as a synthetic parameter to quantify the amount of regularly repeating sEMG waves within the signal itself (bursts). In 5 WLA the sEMG displayed a clear burst activity centred at 11 Hz. These bursts were correlated with force output oscillations and were evident both at 30% and 60% MVC. The MDF decay with time was more evident in WLA than in CG subjects. The %DET increased in WLA, this increase being more evident during 60% MVC contractions. Our results seemed to suggest a special disposition among WLA for the development of long-term changes in firing probability during sub-maximal isometric exercise. The MDF and %DET data provided indications of a greater involvement of fast twitch muscle fibres in WLA than in CG.