Work Volume and Strength Training Responses to Resistive Exercise Improve with Periodic Heat Extraction from the Palm

Abstract

Body core cooling via the palm of a hand increases work volume during resistive exercise. We asked: (a) "Is there a correlation between elevated core temperatures and fatigue onset during resistive exercise?" and (b) "Does palm cooling between sets of resistive exercise affect strength and work volume training responses?" Core temperature was manipulated by 30-45 minutes of fixed load and duration treadmill exercise in the heat with or without palm cooling. Work volume was then assessed by 4 sets of fixed load bench press exercises. Core temperatures were reduced and work volumes increased after palm cooling (Control: Tes = 39.0 ± 0.1° C, 36 ± 7 reps vs. Cooling: Tes = 38.4 ± 0.2° C, 42 ± 7 reps, mean ± SD, n = 8, p < 0.001). In separate experiments, the impact of palm cooling on work volume and strength training responses were assessed. The participants completed biweekly bench press or pull-up exercises for multiple successive weeks. Palm cooling was applied for 3 minutes between sets of exercise. Over 3 weeks of bench press training, palm cooling increased work volume by 40% (vs. 13% with no treatment; n = 8, p < 0.05). Over 6 weeks of pull-up training, palm cooling increased work volume by 144% in pull-up experienced subjects (vs. 5% over 2 weeks with no treatment; n = 7, p < 0.001) and by 80% in pull-up naïve subjects (vs. 20% with no treatment; n = 11, p < 0.01). Strength (1 repetition maximum) increased 22% over 10 weeks of pyramid bench press training (4 weeks with no treatment followed by 6 weeks with palm cooling; n = 10, p < 0.001). These results verify previous observations about the effects of palm cooling on work volume, demonstrate a link between core temperature and fatigue onset during resistive exercise, and suggest a novel means for improving strength and work volume training responses.

Intermittent Palm Cooling’s Impact on Resistive Exercise Performance

“…resistive exercise entails brief bouts of intense activity interspersed with rest periods that afford opportunities to administer palm cooling and obtain data during actual workouts [23]. Prior palm cooling studies assessed cardiovascular and thermal changes yet ignored body heat's impact on pyruvate kinase, an enzyme whose activity declines at high intracellular temperatures [9,14,15,32]. Pyruvate kinase precedes the final glycolytic step in which lactate is formed.…”

“…Due to its dramatic increase in production and subsequent elevations in body temperature, heat is a physiological stressor that sees its concentrations rise from exercise and among individuals (astronauts, military personnel, firefighters, laborers, etc.) exposed to warm environments [9]. Higher body temperatures may cause dehydration that can in turn impair cardiovascular, thermoregulatory and metabolic function [17].…”

“…In theory, placing the palmar surface of one's hand against the surface of a cold object hastens body heat losses. Removal of exerciseinduced heat from the blood by palm cooling should in theory enable that same blood to acquire more heat once it returns to exercising skeletal muscle and/or the body's core [9]. This has led to studies of palm cooling's impact on exercise performance and heat removal.…”

“…This has led to studies of palm cooling's impact on exercise performance and heat removal. To date, palm cooling's impact as an ergogenic aid to exercise is equivocal, as papers did [9,14,32] and did not [7,30] report a benefit. Some claim its ergogenic effects rival those of anabolic steroids [14].…”

“…Some claim its ergogenic effects rival those of anabolic steroids [14]. Many studies assessed palm cooling's impact on aerobic exercise; their research designs usually entailed pre-and post-exercise measurements separated by continuous steady-state activity [8,9,30,32]. Yet resistive exercise may offer a greater challenge to palm cooling's purported ergogenic effects, as it entails higher absolute intensities that may evoke more heat production and vasoconstriction of anastomoses to elicit greater body temperatures [7,9,23].…”