Paul N. Whitehead

Absence of blood oxidative stress in trained men after strenuous exercise.

UNLABELLED Exercise has been noted in some, but not all, studies to elicit an oxidative stress. The discrepancy in findings may be related to differences in exercise intensity across protocols, as well as to differences in training status of participants. PURPOSE We compared blood oxidative stress biomarkers in exercise-trained men after three different bouts of exercise of varying intensity and duration, as well as a nonexercise condition. METHODS On different days, men (n = 12, 21-35 yr) performed aerobic cycle exercise (60 min at 70% HR reserve) and cycle sprints (five 60-s sprints at 100% maximum wattage obtained during graded exercise testing and ten 15-s sprints at 200% maximum wattage obtained during graded exercise testing). Blood was collected before and 0, 30, and 60 min after exercise and analyzed for malondialdehyde, hydrogen peroxide (H(2)O(2)), advanced oxidation protein products, and nitrate/nitrite (NO(x)). As indicators of antioxidant status, Trolox equivalent antioxidant capacity, superoxide dismutase, catalase, and glutathione peroxidase were measured. RESULTS No differences were noted in malondialdehyde, H(2)O(2), advanced oxidation protein product, or NO(x) between conditions or across time (P > 0.05). Antioxidant capacity was generally highest at 30 and 60 min after exercise and lowest at 0 min after exercise. CONCLUSIONS In trained men, and considering the limitations of the current design (e.g., inclusion of selected oxidative stress and antioxidant biomarkers measured in blood only), strenuous bouts of exercise do not result in a significant increase in blood oxidative stress during the 1-h postexercise period. These findings may be related to attenuation in reactive oxygen species production as an adaptation to chronic exercise training and/or a protective effect of the antioxidant system in response to acute strenuous exercise.

Impact of a Dietary Supplement Containing 1,3-Dimethylamylamine on Blood Pressure and Bloodborne Markers of Health: a 10-Week Intervention Study

Background 1,3-dimethylamylamine is a commonly used ingredient within dietary supplements. Our prior work with this agent indicates a transient increase in blood pressure (systolic in particular) following oral ingestion of a single dosage, but no significant increase in resting blood pressure following chronic ingestion. Moreover, intervention studies involving both two and eight weeks of treatment with finished products containing 1,3-dimethylamylamine indicate minimal or no change in bloodborne markers of health. The present study sought to extend these findings by using a 10 -week intervention trial to determine the change in selected markers of health in a sample of men. Methods 25 healthy men were randomly assigned to either a placebo (n = 13) or to a supplement containing 1,3-dimethylamylamine (n = 12) for a period of 10 weeks. Before and after the intervention, resting blood pressure and heart rate were measured, and blood samples were collected for determination of complete blood count, metabolic panel, and lipid panel. Results No significant differences were noted between conditions for blood pressure (P > 0.05), although systolic blood pressure increased approximately 6 mmHg with the supplement (diastolic blood pressure decreased approximately 4 mmHg). A main effect for time was noted for heart rate (P = 0.016), with values decreasing from pre to post intervention. There were significant main effects for time for creatinine (increased from pre to post intervention; P = 0.043) and alkaline phosphatase (decreased from pre to post intervention; P = 0.009), with no condition differences noted (P > 0.05). There was a significant interaction noted for low density lipoprotein cholesterol (LDL-C) (P = 0.043), with values decreasing in the supplement group from pre to post intervention approximately 7 mg · dL-1 (P = 0.034). No other effects of significance were noted for bloodborne variables. Conclusion These data indicate that a dietary supplement containing 1,3-dimethylamylamine does not result in a statistically significant increase in resting heart rate or blood pressure (although systolic blood pressure is increased ~6 mmHg with supplement use). The supplement does not negatively impact bloodborne markers of health. Further study is needed involving a longer intervention period, a larger sample size, and additional measures of health and safety.

Snatch Technique of United States National Level Weightlifters

Abstract Whitehead, PN, Schilling, BK, Stone, MH, Kilgore, JL, and Chiu, LZF. Snatch technique of United States national level weightlifters. J Strength Cond Res 28(3): 587–591, 2014—This study analyzed the top 3 successful snatch attempts by individual lifters in each weight class at a U.S. National Championship weightlifting meet. Two-dimensional (2-D) body position and characteristics of the lifts were compared via 2D video analysis in groups of lifters who displaced forward, showed no displacement, or displaced backward to receive the bar. No significant group differences (p > 0.05) were noted for body mass, bar mass, or hip angle. The rearward displacement group had a significantly greater horizontal distance between the shoulder and heel at the end of the pull (determined as the point where the bar ceases to accelerate vertically). Hip angles for the no displacement group had a small-to-moderate effect size (0.50) in comparison to the forward displacement group, but they only showed a small effect size (0.17) when compared with the rearward displacement group. The forward displacement group showed a small-to-moderate effect size compared with both the no displacement group (0.51) and the rearward displacement group (0.55) concerning the horizontal distance from the shoulder to the heel. These data seem to suggest that rearward displacement in the drop-under phase in the snatch is not detrimental to performance and actually seems to be a preferred technique in U.S. national level lifters. In addition to evidence that rearward displacement is exhibited in elite lifters and is coached globally, it seems this is the preferred technique in international competitions. This technique may be considered a viable variation of the snatch by coaches and athletes of all levels.

Association Of Drop Vertical Jump Displacement With Select Performance Variables

Abstract Feldmann, CR, Weiss, LW, Schilling, BK, and Whitehead, PN. Association of drop vertical jump displacement with select performance variables. J Strength Cond Res 26(5): 1215–1225, 2012—Drop vertical jumps (DVJs) stimulate enhanced countermovement loading as would occur with a run-up before jumping. A variety of performance variables have been associated with DVJ performance including ground contact time (GCT), reactive strength index (RSI), eccentric utilization ratio (EUR), and elasticity index (EI). This study examined the stability reliability and precision of these variables and their associations with DVJ displacement in trained men and women. The EUR and EI measures were redundant, so only EUR findings were reported. Except for EUR, data for all variables were both reliable and precise (intraclass correlation coefficient ≥ 0.70, coefficient of variation [CV%] ⩽ 15.0) although EUR data were precise (CV% ⩽ 15.0). Correlations with DVJ displacement were low for GCT, moderate for RSI, and negligible for EUR. Therefore, GCT and EUR likely represent unique performance characteristics not related to DVJ displacement. Furthermore, the variability in DVJ performance accounted for by RSI may primarily reflect the inclusion of displacement as the numerator in the quotient for calculating it.

The relationship of core strength and activation and performance on three functional movement screens

Abstract Johnson, CD, Whitehead, PN, Pletcher, ER, Faherty, MS, Lovalekar, MT, Eagle, SR, and Keenan, KA. The relationship of core strength and activation and performance on three functional movement screens. J Strength Cond Res 32(4): 1166–1173, 2018—Current measures of core stability used by clinicians and researchers suffer from several shortcomings. Three functional movement screens appear, at face-value, to be dependent on the ability to activate and control core musculature. These 3 screens may present a viable alternative to current measures of core stability. Thirty-nine subjects completed a deep squat, trunk stability push-up, and rotary stability screen. Scores on the 3 screens were summed to calculate a composite score (COMP). During the screens, muscle activity was collected to determine the length of time that the bilateral erector spinae, rectus abdominis, external oblique, and gluteus medius muscles were active. Strength was assessed for core muscles (trunk flexion and extension, trunk rotation, and hip abduction and adduction) and accessory muscles (knee flexion and extension and pectoralis major). Two ordinal logistic regression equations were calculated with COMP as the outcome variable, and: (a) core strength and accessory strength, (b) only core strength. The first model was significant in predicting COMP (p = 0.004) (Pearsons Chi-Square = 149.132, p = 0.435; Nagelkerkes R-Squared = 0.369). The second model was significant in predicting COMP (p = 0.001) (Pearsons Chi-Square = 148.837, p = 0.488; Nagelkerkes R-Squared = 0.362). The core muscles were found to be active for most screens, with percentages of “time active” for each muscle ranging from 54–86%. In conclusion, performance on the 3 screens is predicted by core strength, even when accounting for “accessory” strength variables. Furthermore, it seems the screens elicit wide-ranging activation of core muscles. Although more investigation is needed, these screens, collectively, seem to be a good assessment of core strength.

Coaching and Technology: Live Team Monitoring to Improve Training and Safety

Athletic coaches are always looking for the next strategy or tool to help them gain an advantage over their competitors. In recent years, technology has been incorporated into athletics at all levels. Heart rate monitors are a good example of equipment that has gained significant popularity for individualized training and recovery for athletes. However, a relatively new piece of equipment, the Polar Team Pro system (PTPS), takes technology to the next level by allowing for simultaneous analysis of a group of individuals. The PTPS incorporates global positioning system (GPS) tracking, motion tracking, live heart rate monitoring, and accurate data analysis to be used in a team setting. This article highlights how the PTPS can be used for smart coaching, player development, and safety monitoring of athletes, and provide a cost-effective coaching tool in todays sport setting.