Creatine Supplementation Does Not Increase Peak Power Production and Work Capacity During Repetitive Wingate Testing in Women

This study aimed to evaluate the differences in power production between movement phases (i.e., concentric and eccentric) during the execution of resistance exercises with a flywheel device, differentiating between execution regimes (i.e., bilateral, unilateral dominant leg and unilateral non-dominant leg). Twenty young elite soccer players (U−17) performed two sets of six repetitions of the bilateral half-squat (inertia 0.025 kg·m−2) and the lateral-squat exercise (inertia 0.010 kg·m−2) on a flywheel device. During the testing sessions, mean and peak power in concentric (MPcon) and eccentric (MPecc) phases were recorded. The non-dominant leg showed higher values in all power variables measured, although substantial differences were only found in MPecc (ES = 0.40, likely) and PPcon (ES = 0.36, possibly). On the other hand, for both exercises, MPcon was higher than MPecc (ES = −0.57 to −0.31, possibly/likely greater), while only PPecc was higher than PPcon in the dominant lateral-squat (ES = 0.44, likely). These findings suggest that young soccer players have difficulty in reaching eccentric-overload during flywheel exercises, achieving it only with the dominant leg. Therefore, coaches should propose precise preventive programs based on flywheel devices, attending to the specific characteristics of each limb, as well as managing other variables to elicit eccentric-overload.

Download Full-text

A simple isokinetic cycle for measurement of leg muscle function

Journal of Applied Physiology ◽

10.1152/jappl.1994.77.5.2506 ◽

1994 ◽

Vol 77 (5) ◽

pp. 2506-2510 ◽

Cited By ~ 6

Author(s):

L. C. Lands ◽

L. Hornby ◽

G. Desrochers ◽

T. Iler ◽

G. J. Heigenhauser

Keyword(s):

Exercise Capacity ◽

Strain Gauge ◽

Peak Power ◽

Fixed Time ◽

Work Capacity ◽

Work Output ◽

Widespread Application ◽

Effective Work ◽

Progressive Exercise ◽

Leg Muscle

The measurement of net pedaling torque during isokinetic cycling allows for the evaluation of leg muscle strength and work capacity over fixed time intervals. However, the expense and difficulty of constructing an isokinetic cycle have limited the widespread application of this useful research tool. We have modified a simple commercially available isokinetic cycle that uses hydraulics to maintain pedaling velocity. A strain gauge on the flywheel axle strut measures the torsion on the strut caused by pedaling. To evaluate this device, seven healthy subjects (3 males and 4 females) were each tested twice at 60, 90, and 120 rpm for peak power during a 10-s sprint and at 100 rpm for total work performed during a 30-s sprint. These results were compared with predicted values for age, height, and sex developed on a more complicated isokinetic cycle. Subjects also performed a progressive cycle ergometry test. For the group, peak power was 97.30 +/- 12.64% of predicted (males 883.70 +/- 202.76 W; females 657.00 +/- 66.42 W) and work output was 107.70 +/- 15.75% of predicted (males 15.50 +/- 2.85 kJ; females 11.70 +/- 2.17 kJ), whereas maximal progressive exercise capacity was 126.40 +/- 25.84% (males 245.30 +/- 56.58 W; females 212.30 +/- 35.49 W). The relatively lower work values generated on this cycle (compared with the maximal progressive exercise capacity) can be attributed to the location of the strain gauge, resulting in measurement of effective work output on the flywheel.(ABSTRACT TRUNCATED AT 250 WORDS)

Download Full-text

Effect of supplementation with a cysteine donor on muscular performance

Journal of Applied Physiology ◽

10.1152/jappl.1999.87.4.1381 ◽

1999 ◽

Vol 87 (4) ◽

pp. 1381-1385 ◽

Cited By ~ 95

Author(s):

L. C. Lands ◽

V. L. Grey ◽

A. A. Smountas

Keyword(s):

Oxidative Stress ◽

Young Adults ◽

Placebo Group ◽

Peak Power ◽

Work Capacity ◽

Muscular Fatigue ◽

Antioxidant Defenses ◽

Testing Measuring ◽

Muscular Performance

Oxidative stress contributes to muscular fatigue. GSH is the major intracellular antioxidant, the biosynthesis of which is dependent on cysteine availability. We hypothesized that supplementation with a whey-based cysteine donor [Immunocal (HMS90)] designed to augment intracellular GSH would enhance performance. Twenty healthy young adults (10 men, 10 women) were studied presupplementation and 3 mo postsupplementation with either Immunocal (20 g/day) or casein placebo. Muscular performance was assessed by whole leg isokinetic cycle testing, measuring peak power and 30-s work capacity. Lymphocyte GSH was used as a marker of tissue GSH. There were no baseline differences (age, ht, wt, %ideal wt, peak power, 30-s work capacity). Follow-up data on 18 subjects (9 Immunocal, 9 placebo) were analyzed. Both peak power [13 ± 3.5 (SE) %, P < 0.02] and 30-s work capacity (13 ± 3.7%, P < 0.03) increased significantly in the Immunocal group, with no change (2 ± 9.0 and 1 ± 9.3%) in the placebo group. Lymphocyte GSH also increased significantly in the Immunocal group (35.5 ± 11.04%, P < 0.02), with no change in the placebo group (−0.9 ± 9.6%). This is the first study to demonstrate that prolonged supplementation with a product designed to augment antioxidant defenses resulted in improved volitional performance.

Download Full-text

SOUTH PATAGONIA: WIND/HYDROGEN/COAL SYSTEM WITH REDUCED CO2 EMISSIONS

Alternative Energy and Ecology (ISJAEE) ◽

10.15518/isjaee.2018.22-24.080-087 ◽

2018 ◽

pp. 80-87

Author(s):

G. Spazzafumo

Keyword(s):

Carbon Dioxide ◽

Renewable Energy ◽

Peak Power ◽

Coal Gasification ◽

Electrical Power ◽

Electrical Energy ◽

Power Production ◽

Energy System ◽

Underground Coal Gasification ◽

South Patagonia

Wind is a significant renewable energy source in Patagonia, which could generate a very large amount of electrical energy. However, it is not possible to put such a large amount of energy on to the grid due to instability issues. Electrolysis could facilitate the storage of such energy in the form of hydrogen, which could be used for peak power production or for vehicles. However, hydrogen storage and distribution are still very expensive. On the other hand, South Patagonia has reserves of coal which exploitation is not easy. One solution could be underground coal gasification. Unfortunately, using coal results in high emissions of carbon dioxide. Hydrogen from wind energy could be the solution to convert coal to methane and to eventually generate electrical power. In this way, a large amount of renewable energy could be introduced to the energy system with a reduction in the emissions of carbon dioxide.

Download Full-text

Effect of oral creatine supplementation on power output and fatigue during bicycle ergometry

Journal of Applied Physiology ◽

10.1152/jappl.1995.78.2.670 ◽

1995 ◽

Vol 78 (2) ◽

pp. 670-673 ◽

Cited By ~ 82

Author(s):

W. H. Cooke ◽

P. W. Grandjean ◽

W. S. Barnes

Keyword(s):

Power Output ◽

High Intensity ◽

Peak Power ◽

Creatine Supplementation ◽

Total Work ◽

Fatigue Index ◽

Bicycle Ergometry ◽

Double Blind ◽

Mean Values ◽

Time To Peak

Our purpose was to determine the effect of oral creatine supplementation on exercise performance during high-intensity short-duration bicycle sprinting. Power output was recorded for 12 healthy untrained males (age 24.08 +/- 0.53 yr, weight 81.22 +/- 1.32 kg) before and after 5 days of creatine (n = 6) or placebo (n = 6) supplementation. A double-blind research design was employed. Subjects performed maximal sprints against a constant load (111.8 N) for 15 s. Each one-half pedal revolution was magnetically counted, and subsequent measurements of peak power, time to peak power, total work, and the fatigue index were digitized and stored on disk. Mean values for peak power, time to peak power, total work, and fatigue index were 958.01 +/- 40.66 W, 4.09 +/- 0.82 s, 11.28 +/- 0.46 kJ, and 32.1 +/- 1.58% decline from peak power, respectively. No significant differences were observed within or between groups before or after supplementation for any of the mechanical parameters measured (P > 0.05). These findings suggest that oral creatine supplementation does not positively affect power output or fatigue during continuous high-intensity bicycle exercise in untrained men.

Download Full-text

Oral Creatine Supplementation and Upper Extremity Anaerobic Response in Females

International Journal of Sport Nutrition and Exercise Metabolism ◽

10.1123/ijsnem.10.3.277 ◽

2000 ◽

Vol 10 (3) ◽

pp. 277-289 ◽

Cited By ~ 6

Author(s):

Karyn L. Hamilton ◽

Michael C. Meyers ◽

William A. Skelly ◽

Robert J. Marley

Keyword(s):

Upper Extremity ◽

Significant Interaction ◽

Peak Velocity ◽

Univariate Analysis ◽

Creatine Supplementation ◽

Elbow Flexion ◽

Work Capacity ◽

Sports Performance ◽

Isokinetic Torque ◽

To Receive

The purpose of this study was to investigate the influence of creatine monohydrate () on upper extremity anaerobic response in strength-trained females involved in overhand sports. Two movements were utilized in this evaluation: elbow flexion (EF) and shoulder internal rotation (IR). Subjects were pair-matched and assigned to receive placebo (n = 13) or 25 g (n = 11) for 7 days. Pre- and post-treatment measurements included peak concentric and eccentric isokinetic torque, isotonic 1RM, and fatigue (FAT) during EF; isotonic 1RM, FAT, and peak velocity during IR; and body weight. MANOVAs revealed significant interaction between treatment and trial for EF (p < .05) but not for IR or weight. Univariate analysis indicated a significantly greater change in following than following placebo. Thus, did not influence peak EF or IR strength, IR work to fatigue, or IR velocity, but was associated with greater work capacity during fatiguing EF. These data suggest that may enhance upper extremity work capacity, but this enhancement may not extend to the muscles primarily responsible for overhand sports performance.

Download Full-text

Sled Towing: The Optimal Overload for Peak Power Production

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2016-0602 ◽

2017 ◽

Vol 12 (8) ◽

pp. 1052-1058 ◽

Cited By ~ 12

Author(s):

Andrea Monte ◽

Francesca Nardello ◽

Paola Zamparo

Keyword(s):

Contact Time ◽

Peak Power ◽

Stride Length ◽

Power Production ◽

Step Length ◽

Flight Time ◽

Sprint Training ◽

Joint Angles ◽

Step Number ◽

Increasing Load

Purpose:The effects of different loads on kinematic and kinetic variables during sled towing were investigated with the aim to identify the optimal overload for this specific sprint training.Methods:Thirteen male sprinters (100-m personal best: 10.91 ± 0.14 s) performed 5 maximal trials over a 20-m distance in the following conditions: unloaded and with loads from 15% to 40% of the athlete’s body mass (BM). In these calculations the sled mass and friction were taken into account. Contact and flight times, stride length, horizontal hip velocity (vh), and relative angles of hip, knee, and ankle (at touchdown and takeoff) were measured step by step. In addition, the horizontal force (Fh) and power (Ph) and maximal force (Fh0) and power (Ph0) were calculated.Results:vh, flight time, and step length decreased while contact time increased with increasing load (P < .001). These variables changed significantly also as a function of the step number (P < .01), except between the 2 last steps. No differences were observed in Fh among loads, but Fh was larger in sled towing than in unloaded. Ph was unaffected by load up to +20%BM but decreased with larger loads. Fh0 and Ph0 were achieved at 20%BM. Up to 20%BM, no significant effects on joint angles were observed at touchdown and takeoff, while at loads >30%BM joint angles tended to decrease.Conclusion:The 20%BM condition represents the optimal overload for peak power production—at this load sprinters reach their highest power without significant changes in their running technique (eg, joint angles).

Download Full-text