Resistance training (RT) is currently endorsed by several medical associations for various health benefits including a reduced cardiovascular response when lifting an object of a given mass. This suggests a reduced workload on the heart, and could potentially benefit individuals susceptible for heart disease, especially when performing physical activity under adverse conditions such as extreme hot or cold weather. However, to our knowledge this finding has not been translated into a combined aerobic and lifting task (e.g. carrying groceries). Therefore the primary purpose of this study was to investigate the effect of RT on various cardiovascular parameters in the cold, while performing a combined aerobic and lifting exercise. A secondary purpose was to examine resting arterial stiffness and QT interval following the training.
Twenty-eight healthy sedentary males were randomized into either a standardized resistance training program (n=15) or control (n=13). The total body program consisted of 3 days per week, for 8 weeks, at intensities of 50-80% initial one repetition maximal. Subjects presented to the lab on two separate days prior to randomization and again following the
intervention. Day 1 testing consisted mainly of fitness measurements, while day 2 involved the various cardiovascular measures at rest and during exercise inside the cold
environmental chamber (5 0C). The cardiovascular variables of interest were: QTc interval, arterial stiffness, rate pressure product (RPP), cardiac output, stroke volume, and
total peripheral resistance. The exercise task consisted of 5 minutes of treadmill walking while carrying a moderately heavy hand weight.
Post-test analysis revealed an attenuated RPP during exercise for the RT group compared to the control group (p=0.048). Additionally, resting values for QTc under euthermic and cold conditions showed a significant interaction (p<0.05) with a reduction in the RT group and a concomitant increase in the control. Resting arterial stiffness as measured by pulse pressure/stroke volume did not change over time for either group
The main finding of this study suggests that RT attenuates the myocardial demand of carrying an absolute weight in a cold environment. These findings, along with the observed reductions in QTc, support current medical guidelines regarding the cardiovascular benefits of RT.