This investigation evaluated the effect of oral potassium phosphate supplementation on ratings of perceived exertion (RPE) and physiological responses during maximal graded exercise tests (GXT). Eight highly trained endurance runners completed a GXT to anchor the Borg 15-point RPE scale and two double-blind counterbalanced GXTs. Subjects ingested either 4,000 mg · day−1 of phosphate (PHOS) or a placebo (PLA) for 2 days. Two weeks separated GXTs. Phosphate levels obtained immediately prior to the GXTs were greater in PHOS than PLA. No differences between PHOS and PLA were noted for the submaximal and maximal physiological responses. RPE for the overall body were lower during PHOS than PLA at intensities corresponding to 70–80% of V̇O2max. This suggests that oral potassium phosphate supplementation mediates perceived exertion during moderately intense exercise.
Fredric Goss, Robert Robertson, Steve Riechman, Robert Zoeller, Ibrahim Dabayebeh, Niall Moyna, Nicholas Boer, Jennifer Peoples and Kenneth Metz
Jacob A. Goldsmith, Cameron Trepeck, Jessica L. Halle, Kristin M. Mendez, Alex Klemp, Daniel M. Cooke, Michael H. Haischer, Ryan K. Byrnes, Robert F. Zoeller, Michael Whitehurst and Michael C. Zourdos
Purpose: To examine the validity of 2 linear position transducers, the Tendo Weightlifting Analyzer System (TWAS) and Open Barbell System (OBS), compared with a criterion device, the Optotrak Certus 3-dimensional motion-capture system (OC3D). Methods: A total of 25 men (age, 25  y; height, 174.0 [6.7] cm; body mass, 89.0 [14.7] kg; squat 1-repetition maximum [1RM], 175.8 [34.7] kg) with ≥2 y of resistance-training experience completed a back 1RM and 1 set to failure at 70% of 1RM. Average concentric velocity (ACV) and peak concentric velocity (PCV) were recorded by all 3 devices during the final warm-up set, all 1RM attempts, and every repetition during the 70% set. Results: In total, 575 samples were obtained. Bland–Altman plots, mountain plots, a 1-way analysis of variance, SEM, and intraclass correlation coefficients were used to analyze validity. The analysis of variance showed no difference (P = .089) between devices for ACV. However, for PCV, TWAS was significantly different (ie, inaccurate) from OC3D (P < .001) and OBS (P = .001), but OBS was similar (P = .412) to OC3D. For ACV, intraclass correlation coefficients were higher for OBS than for TWAS. Bland–Altman plots showed agreement for ACV for both devices against OC3D but large limits of agreement for PCV for both devices. Mountain plots showed valid ACV for both devices, however, but slightly greater ACV and PCV accuracy with OBS than TWAS. Conclusions: Both devices may provide valid ACV measurements, but some metrics suggest more accurate ACV with OBS vs TWAS. For PCV, neither device is particularly accurate; however, OBS seems to be more accurate than TWAS.
Joshua Lowndes, Robert F. Zoeller, George A. Kyriazis, Mary P. Miles, Richard L. Seip, Niall M. Moyna, Paul S. Visich, Linda S. Pescatello, Paul M. Gordon, Paul D. Thompson and Theodore J. Angelopoulos
The purpose of this study was to examine whether leptin levels affect the response of leptin to exercise training (ET) and whether this is also affected by C-reactive protein (CRP) or the three common Apolipoprotein E genotypes (APOE). Ninety-seven (male = 45, female = 52) sedentary individuals underwent 6 months of supervised ET. Blood was sampled before the initiation of ET, and again 24 and 72 hr after completion of the final training session. ET resulted in a small reduction in body mass (80.47 ± 18.03 vs 79.42 ± 17.34 kg, p < .01). Leptin was reduced 24 hr after the final exercise session (p < .01), but returned to normal after 72 hr (p > .05)—Pre: 13.51 ± 12.27, 24hr: 12.14 ± 12.34, 72hr: 12.98 ± 11.40 ng/ml. The most hyperleptinemic individuals had a greater initial response, which was sustained through to 72 hr after the final session in the pooled study population (p < .01), and in both males (p < .05) and females (p < .05) separately. CRP was related to leptin independently of body weight and positively related to the reductions in leptin. APOE genotype was not related to leptin levels and did not affect the response to ET. Leptin levels may only be reduced by ET in those with hyperleptinemia. In addition, both the initial extent of hyperleptinemia and the subsequent reduction in leptin may be related to low grade chronic systemic inflammation.