Malcolm T. Whitehead

Comparison of glycerol and water hydration regimens on tennis-related performance.

PURPOSE To compare glycerol and water hyperhydration and rehydration on tennis related skill and agility performance. METHODS Eleven male subjects completed two counter-balanced, double-blind trials. Each trial consisted of three phases: 1). hyperhydration with or without glycerol (1.0 g.kg/(-1)) over 150 min, 2). 120 min of exercise-induced dehydration (EID), and 3) rehydration with or without glycerol (0.5 g.kg(-1)) over 90 min. After each phase, subjects performed 5- and 10-m sprint tests, a repeated-effort agility test, and tennis skill tests. RESULTS Glycerol (G) hyperhydration significantly increased fluid retention by approximately 900 mL over the placebo (P) (P<or= 0.05). After EID, body weight was reduced in both groups but was not significantly different between groups (G: -2.71 +/- 0.08, P: -2.67 +/- 0.09%). At the end of the rehydration phase, PV was significantly greater in the G trial than in the P trial, and the G trial resulted in a significantly greater fluid retention of approximately 700 mL over the P trial ( P<or= 0.05). Although the magnitude of hypohydration was modest (<3%), sprint times were significantly slower after the EID ( P<or= 0.05) compared with post hyperhydration and post rehydration but were not significantly different between trials. No significant difference existed between groups and across time for the repeated effort agility tests and groundstrokes and serve tests. CONCLUSION The data demonstrate that relatively modest hypohydration ( approximately 2.7%) as a result of EID, significantly slows 5- and 10-m sprint times. Furthermore, although the glycerol hydration regimen provided a better hydration status than the placebo hydration regimen, no performance benefits were observed.

Effect of moderate dehydration on torque, electromyography, and mechanomyography

The purpose of the present investigation was to test the hypotheses that the mechanomyographic (MMG) signal would be affected by hydration status due to changes in the intra‐ and extracellular fluid content (which could affect the degree of fluid turbulence), changes in the filtering properties of the tissues between the MMG sensor and muscle, and changes in torque production that may accompany dehydration. Ten subjects (age 22.5 ± 1.6 years) were tested for maximal isometric (MVC), submaximal isometric (25, 50, and 75%MVC), and maximal concentric isokinetic muscle strength of the biceps brachii in either a euhydrated or dehydrated state while the electromyographic (EMG) and MMG signals were recorded. Separate three‐way and two‐way ANOVAs indicated no change in torque, EMG amplitude, EMG mean power frequency (MPF), MMG amplitude, and MMG MPF with dehydration. The lack of dehydration effect suggests that MMG may be more reflective of the intrinsic contractile processes of a muscle fiber (torque production) or the motor control mechanisms (reflected by the EMG) than the tissues and fluids surrounding the muscle fiber.

Running economy and maximal oxygen consumption after 4 weeks of oral Echinacea supplementation.

Abstract Whitehead, MT, Martin, TD, Scheett, TP, and Webster, MJ. Running economy and maximal oxygen consumption after 4 weeks of oral Echinacea supplementation. J Strength Cond Res 26(7): 1928–1933, 2012—The purpose of this investigation was to determine the effects of 4 weeks of oral Echinacea (ECH) supplementation on erythropoietin (EPO), red blood cell (RBC) count, running economy (RE), and V[Combining Dot Above]O2max. Twenty-four men aged 24.9 ± 4.2 years, height 178.9 ± 7.9 cm, weight 87.9 ± 14.6 kg, body fat 19.3 ± 6.5% were grouped using a double-blind design and self-administered an 8,000-mg·d−1 dosage of either ECH or placebo (PLA) in 5 × 400 mg × 4 times per day for 28 days. Blood samples were collected and analyzed for RBCs and EPO using automated flow cytometery and enzyme-linked immunosorbent assay. Maximal graded exercise tests (GXTs) were administered to measure V[Combining Dot Above]O2max, RE, and heart-rate responses. Analysis of variance was used to determine statistically significant differences (P ⩽ 0.05). The EPO increased significantly in ECH at 7 days (ECH: 15.75 ± 0.64, PLA: 10.01 ± 0.73 mU·ml−1), 14 days (ECH: 18.88 ± 0.71, PLA: 11.02 ± 0.69 mU·ml−1), and 21 days (ECH: 16.06 ± 0.55, PLA: 9.20 ± 0.55 mU·ml−1). V[Combining Dot Above]O2max increased significantly in ECH (ECH: 1.47 ± 1.28, PLA: −0.13 ± 0.52%). Running economy improved significantly in ECH as indicated by a decrease in submaximal V[Combining Dot Above]O2 during the first 2 stages of the GXT (stage 1: ECH −1.50 ± 1.21, PLA 0.60 ± 1.95%; stage 2: ECH −1.67 ± 1.43, PLA 0.01 ± 1.03%). These data suggest that ECH supplementation results in significant increases in EPO, V[Combining Dot Above]O2max, and running economy.

The effect of glycerol on torque, electromyography, and mechanomyography.

The purpose of this investigation was to determine the effect of hyperhydration on the electromyographic (EMG) and mechanomyographic (MMG) responses during isometric and isokinetic muscle actions of the biceps brachii. Eight (22.1 ± 1.8 years, 79.5 ± 22.8 kg) subjects were tested for maximal isometric, submaximal isometric, and maximal concentric isokinetic muscle strength in either a control (C) or hyperhydrated (H) state induced by glycerol ingestion while the EMG and MMG signals were recorded. Although fluid retention was significantly greater during the H protocol, the analyses indicated no change in torque, EMG amplitude, EMG mean power frequency (MPF), MMG amplitude, or MMG MPF with hyper-hydration. These results indicated that glycerol-induced fluid retention does not affect the torque-producing capabilities of a muscle, the impulses (EMG) going to a muscle, or muscular vibrations (MMG). It has been suggested that EMG and MMG can be used as direct electrical/mechanical monitoring, which could be presented to trainers and athletes; however, before determining the utility of these signals, the MMG and EMG responses should be examined under a variety of conditions such as in the present study.

Establishing the Learned Effect of Repeated Wingate Anaerobic Tests: 774 Board #170 May 27, 2

The Wingate anaerobic test (WAnT) is a recognized and well-established measure of power output, muscular endurance, and fatigue. However, a learning effect could reduce the reliability of these measures. PURPOSE: To establish the number of WAnT trials needed to produce a learned effect. METHODS: Thirty-six apparently healthy college-aged men (n=20) and women (n=16) who had not previously performed a WAnT participated in five WAnT trials separated by a minimum of 72 hours. Peak Power (PP) and Mean Power (MP) were recorded for each trial. Resistance for trials was calculated at 7.5% of each respective participant’s weight. RESULTS: In men, paired samples t-test revealed PP increased on all trials (2-5) when compared to trial 1 (+44.66W, +49.19W, +55.80W, +63.95W; p=0.02, p=0.01, p=0.01, p=0.00, respectively). PP significantly increased from trial 1 to trial 2 (849.21±127.41 watts to 893.87±143.92 watts, p .05). The same results were found for MP, with a significant increase from trial 1 to 2 (627.90±79.01 watts to 660.04±79.66 watts, p .05). There was a trend toward an elicited peak MP at trial 3 (p=.09, Cohen’s d= -.83). In women, the average PP and MP for trial 1 was 547.74±94.56 watts and 415.91±68.21 watts, respectively, with no significant differences found between trials (p>.05). These results suggest that a learned effect is present within PP and MP until trial 2 of the WAnT, with a trend toward peak MP at trial 3 for male participants. CONCLUSION: Thereby, suggesting that when performing WAnT, utilizing less than 3 practice trials might elicit significant power increase in male participants due to this learned effect. Current data suggests that female participants elicit peak power at trial 1 of the WAnT, with no significant increase in subsequent trials. Additional research should be conducted in order to further investigate the non-significant trend of increasing power output across WAnT trials in male participants as well the lack of female learned response.