Postactivation Potentiation Effect of Heavy Sled Towing on Subsequent Sprints.

ABSTRACT: Williams, JJ, Heron, R, Spradley, B, and Saracino, P. Postactivation potentiation effect of heavy sled towing on subsequent sprints. J Strength Cond Res 35(5): 1229-1233, 2021-Recent research supports heavy sled towing as a tool used to improve subsequent sprints as part of postactivation potentiation (PAP) protocols. The purpose of this study was to examine the effect of heavy sled towing using a velocity decrement (Vdec) on subsequent unloaded sprinting in high school football (soccer) athletes sprinting on artificial turf. A sled load equating to a 40-50% Vdec range was used (66-70% body mass). Fifteen (n = 9 boys and n = 6 girls) high school football players volunteered for this study. The sled-towing intervention consisted of a dynamic warm-up, 3 submaximal sprint efforts (50, 75, and 95%), and 3 maximum speed 15-m sled sprints, separated by 2-minute rests, of which the fastest time was recorded for analysis. Peak preintervention 15-m baseline sprint times were compared with peak post sled-towing 15-m sprint times using a paired samples t-test. Thirteen of 15 athletes ran faster peak post sled-towing sprint times than peak preintervention baseline sprint times (9 boys and 4 girls). On average, peak post sled-towing sprint times (2.60 ± 0.10 seconds) were 0.10 seconds faster (p < 0.0001; Cohen's d = 0.92) than peak preintervention baseline sprint times (2.70 ± 0.09 seconds). This research established that sled-towing protocols using loads corresponding to Vdec of 40-50% significantly improved subsequent sprints in high school football (soccer) athletes running on artificial turf.

Acetylsalicylic acid does not alter thermo-effector responses during mild whole-body passive heat stress in young men.

Acetylsalicylic acid (ASA), aspirin, exerts potent systemic effects that may interfere with normal thermo-effector responses. We investigated the influence of commonly ingested ASA doses on measures of skin blood flow (SkBF) and local sweat rate (SR) during whole-body, passive heat stress. Seven male participants completed counter-balanced trials to compare ASA treatments (single dose 325 mg or 4 consecutive days 81 mg (4-d 81 mg)) to control (no ASA). Laser-Doppler flowmetry provided an index of SkBF. A ventilated capsule measured local sweat rate via capacitance hygrometry. Mean body temperature ([Formula: see text]) was increased by 1 °C above baseline using a water-perfused suit. [Formula: see text] was similar at the onset of cutaneous vasodilation among trials. Cutaneous vascular conductance, expressed as a percentage change from baseline, was not different among trials. Additionally, [Formula: see text] at the onset of local SR and SR sensitivity did not differ among trials. While ASA has previously been shown to influence SkBF during heat stress, it is possible our cohort's relatively young age may have contributed to our dissimilar results.