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Karin Roeleveld, Eric Lute, Dirkjan Veeger, Luc van der Woude and Tom Gwinn

To assess power output, force application, and kinematics of wheelchair propulsion in peak exercise, nine wheelchair athletes with medical lesion levels of T8 or lower performed a 30-s sprint test on a stationary wheelchair ergometer. Mean power output, calculated for the right wheel only, was 59.4 ± 8.5 W. The ratio between effective force and total propulsive force was 60 ± 6%. A negative torque around the hand and a not tangentially directed total force accounted for this low effectiveness. Since the subject group was highly trained, their technique was considered to be optimal for the given circumstances. Therefore, athletes who want to improve power output by increasing effectiveness should keep in mind the existence of a nontangential propulsive force and a braking torque applied by the hands onto the hand rim surface. It is likely that both aspects will be influenced by the geometry of the wheelchair, for example, hand rim dimension or seat position.

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Terry J. Housh, Glen O. Johnson and Dona J. Housh

The purpose of this investigation was to examine age related changes in muscular power of high school wrestlers. A total of 155 high school wrestlers (M age±SD = 16.5±2.4 yrs) volunteered as subjects for this investigation. The sample included only wrestlers who were ≤ 16.00 years (younger group, n=75) or >17.00 years (older group, n=80). All subjects completed a Wingate anaerobic test to determine mean (MP) and peak (PP) power as well as underwater weighing for body composition assessment. The results indicated significant (p<0.05) group differences for absolute MP and PP but no differences when adjusted for BW and FFW. Thus the enhanced muscular power in the older group of high school wrestlers was associated with increases in BW and FFW.

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Nicholas Caplan and Trevor N. Gardner

The aim of the present study was to determine the effect of varying the height of the foot stretcher on the mechanical effectiveness of rowing. Ten male university level rowers rowed maximally for 3 minutes 30 seconds on a modified Concept 2 rowing ergometer. Each participant completed one trial at three foot stretcher heights. Position 1 was the original Concept 2 stretcher position, with Position 2 being located 5 cm and Position 3 being 10 cm above the original position and in the same orientation. Pull force and velocity were measured, and mean power generated by the rowers was calculated for each stroke. It was shown that in all three stretcher positions, mean power per stroke decreased as a function of time during the trial, confirming the fatiguing effects of the task. Although mean power per stroke did not differ significantly between stretcher positions at the start of the trial, p = 0.082, a significant difference was observed between the original stretcher position and Positions 2 and 3 at the end of the trial, p < 0.05. The lowest decline in mean power occurred in the highest stretcher position. It is suggested that this improvement in effectiveness is due to a reduction in the active downward vertical forces applied to the foot stretchers which does not contribute to forward propulsion, and thus a reduction in energy waste during each stroke. It was hypothesized that further raising the stretchers will continue to lead to an improvement in effectiveness until the optimum stretcher height is reached, above which effectiveness will be reduced.

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Nicola Giovanelli, Filippo Vaccari, Mirco Floreani, Enrico Rejc, Jasmine Copetti, Marco Garra, Lea Biasutti and Stefano Lazzer

massagers. SMFR can promote short-term flexibility improvement, and it does not seem to have negative effects on performance. 2 , 3 , 9 – 11 In fact, no differences in maximal force and power were detected after an SMFR protocol. 2 , 12 Moreover, SMFR has been shown effective for reducing delayed

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Seihati A. Shiroma, Ursula F. Julio and Emerson Franchini

supplementary aerobic training program, judo athletes presented faster V ˙ O 2 recovery after a maximal graded exercise test (GET) and faster heart rate (HR) recovery after a high-intensity judo-specific test. 8 Thus, aerobic power development has been associated with faster creatine phosphate resynthesis

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Pedro Jiménez-Reyes, Fernando Pareja-Blanco, Carlos Balsalobre-Fernández, Víctor Cuadrado-Peñafiel, Manuel A. Ortega-Becerra and Juan J. González-Badillo

Purpose:

To examine the relationship between the relative load in full squats and the height achieved in jump-squat (JS) exercises and to determine the load that maximizes the power output of high-level athletes.

Method:

Fifty-one male high-level track-and-field athletes (age 25.2 ± 4.4 y, weight 77. ± 6.2 kg, height 179.9 ± 5.6 cm) who competed in sprinting and jumping events took part in the study. Full-squat 1-repetition-maximum (1-RM) and JS height (JH) with loads from 17 to 97 kg were measured in 2 sessions separated by 48 h.

Results:

Individual regression analyses showed that JH (R 2 = .992 ± .005) and the jump decrease (JD) that each load produced with respect to the unloaded countermovement jump (CMJ) (R 2 = .992 ± 0.007) are highly correlated with the full-squat %1-RM, which means that training intensities can be prescribed using JH and JD values. The authors also found that the load that maximizes JS’s power output was 0%RM (ie, unloaded CMJ).

Conclusions:

These results highlight the close relationship between JS performance and relative training intensity in terms of %1-RM. The authors also observed that the load that maximizes power output was 0%1-RM. Monitoring jump height during JS training could help coaches and athletes determine and optimize their training loads.

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Trynke Hoekstra, Colin A. Boreham, Liam J. Murray and Jos W.R. Twisk

Background:

It is not clear what the relative contribution is of specific components of physical fitness (aerobic and muscular) to cardiovascular disease (CVD) risk. We investigated associations between aerobic fitness (endurance) and muscular fitness (power) and CVD risk factors.

Methods:

Data were obtained from the Young Hearts project, a representative sample of 12- and 15-year-old boys and girls from Northern Ireland (N = 2016). Aerobic fitness was determined by the 20-m shuttle run test, muscular fitness by the Sargent jump test. CVD risk factors included sum of skinfolds, systolic and diastolic blood pressure, serum total cholesterol (TC), HDL cholesterol, and TC:HDL ratio. Several linear regression analyses were conducted for 4 age and gender groups separately, with the risk factor as the outcome variable.

Results:

Significant associations between aerobic fitness and a healthy CVD risk profile were found. These observed relationships were independent of power, whereas the (few) relationships between muscular fitness and the risk factors were partly explained by endurance.

Conclusions:

Tailored, preventive strategies during adolescence, incorporating endurance rather than power sports, could be encouraged to help prevent CVD. This is important because existing studies propose that healthiness during adulthood is founded on healthiness in adolescence.

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Harsh H. Buddhadev and Philip E. Martin

studies have examined the effects of external power output and cadence on aerobic demand or energy expenditure ( Belli & Hintzy, 2002 ; Bigland-Ritchie & Woods, 1974 ; Chavarren & Calbet, 1999 ; Gaesser & Brooks, 1975 ; Marsh & Martin, 1993 ; Samozino, Horvais, & Hintzy, 2006 ). Influences of power

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Dennis van Erck, Eric J. Wenker, Koen Levels, Carl Foster, Jos J. de Koning and Dionne A. Noordhof

the maximal oxygen uptake [ V ˙ O 2 max] and V ˙ O 2 at the lactate threshold), performance O 2 deficit, and gross mechanical efficiency (GE). GE, defined as the percentage of metabolic power input, that is, converted into mechanical power output (PO), is considered the most valid definition of

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Liam P. Kilduff, Huw Bevan, Nick Owen, Mike I.C. Kingsley, Paul Bunce, Mark Bennett and Dan Cunningham

Purpose:

The ability to develop high levels of muscle power is considered an essential component of success in many sporting activities; however, the optimal load for the development of peak power during training remains controversial. The aim of the present study was to determine the optimal load required to observe peak power output (PPO) during the hang power clean in professional rugby players.

Methods:

Twelve professional rugby players performed hang power cleans on a portable force platform at loads of 30%, 40%, 50%, 60%, 70%, 80%, and 90% of their predetermined 1-repetition maximum (1-RM) in a randomized and balanced order.

Results:

Relative load had a significant effect on power output, with peak values being obtained at 80% of the subjects’ 1-RM (4466 ± 477 W; P < .001). There was no significant difference, however, between the power outputs at 50%, 60%, 70%, or 90% 1-RM compared with 80% 1-RM. Peak force was produced at 90% 1-RM with relative load having a significant effect on this variable; however, relative load had no effect on peak rate of force development or velocity during the hang power clean.

Conclusions:

The authors conclude that relative load has a significant effect on PPO during the hang power clean: Although PPO was obtained at 80% 1-RM, there was no significant difference between the loads ranging from 40% to 90% 1-RM. Individual determination of the optimal load for PPO is necessary in order to enhance individual training effects.