The influence of interval versus continuous exercise on thermoregulation, torso hemodynamics, and finger dexterity in the cold

Abstract

The purpose of this study was to evaluate how interval (INT) and continuous (CONT) exercise alter body temperatures and manual dexterity in the cold (5 degrees C). Fourteen young men underwent two trials consisting of a 90-min period of acute cold exposure (ACE), 30 min of exercise (INT or CONT), and a 60-min recovery period (REC). Participants donned approximately 1 clo but the hands remained bare for the entire protocol so that a steep decline in dexterity performance occurred prior to the initiation of exercise. INT and CONT were isoenergetic, reflecting 50 +/- 1% of each individual's VO(2) peak. Rectal (Tre) and skin temperatures were monitored continuously and dexterity testing was conducted at ten time points throughout each 3-h trial. In addition, oxygen consumption (VO(2)) and torso hemodynamics were assessed via indirect calorimetry and impedance cardiography (ICG), respectively. As expected, finger temperature and dexterity declined during ACE, relative to baseline. Both modes of exercise increased finger temperature and dexterity, relative to ACE. However, CONT was more effective than INT at increasing finger temperature on the dominant hand, which was associated with better dexterity scores during REC. Tre was not different between trials but a significant increase in stroke volume was found following CONT. Perhaps elevated stroke volume during post-exercise REC plays a role in finger rewarming and dexterity performance. Further mechanistic studies are needed to confirm the role of cardiovascular function in the enhancement of manual performance in the cold.

Cold Stress Effects on Exposure Tolerance and Exercise Performance

“…Exercise has also been shown to improve dexterity. Muller et al (168) reported that working at 50% VO 2peak for 30 min performed in the middle of a 5 • C coldair exposure increased dexterity by ∼25%, although it did not approach the baseline levels that were measured in a temperate environment. In contrast, cold habituation, either through natural exposure or laboratory cold-water immersions, has not been shown to improve manual dexterity (114,169).…”

Effect of healthy aging on renal vascular responses to local cooling and apnea

“…The CPT is a widely used laboratory stimulus that increases sympathetic outflow to skeletal muscle (32,70) and increases myocardial oxygen demand (45,48). From a practical standpoint, people exposed to cold ambient conditions also experience hand pain (52) and reduced manual dexterity (53), thereby increasing their risk for accident (19). Thus physiological and perceptual responses to hand cooling have clinical and occupational applications.…”

Pain and thermal sensation in the cold: the effect of interval versus continuous exercise

“…Participants were immediately excluded if they reported cardiovascular or metabolic disease or were taking any medications. They were of average aerobic fitness (44.7 ± 5 mL/kg/min) and body fatness (14.5 ± 4.9%) as determined via VO 2 peak test (cycle ergometry) and seven-site skinfold (mean = 153 ± 55 mm), respectively (Muller et al 2010). The protocol was approved by the Kent State University Institutional Review Board and all volunteers gave signed informed consent.…”

“…Similarly, it has been shown that moderate exercise (cycle ergometry) can improve finger dexterity following immobility in 5°C. When core and skin temperature increased, fine motor performance improved (Muller et al 2010). However, it is yet to be determined how the mode of exercise (interval vs. continuous, matched for energy expenditure) affects thermal sensation and hand pain.…”

“…It must be noted that this report is from a larger investigation that evaluated a number of physiological, cognitive, and manual performance variables during three total hours of ACE, exercise, and REC in 5°C. The 14 subjects reported herein are the same individuals as before (Muller et al 2010).…”