CARDIAC DEMANDS OF HEAVY SNOW SHOVELING

Objective.-To assess the physiologic responses to manual (shoveling) v s automated (electric snow thrower) snow removal in healthy, untrained men. Design.-Observational, controlled trial. Setting.-A community-ba sed, acute care, teaching-research hospital. Participants.-A volunteer sample of 10 apparently healthy untrained men (mean+/-SD age = 32.4+/ -2.1 years) met all eligibility criteria and completed the study. Inte rvention.-Each subject cleared two 10+/-2-cm-high, 15-m-long tracts of heavy, wet snow in the cold (2 degrees C), using self-paced manual an d automated methods, in random order, with 10- to 15-minute rest perio ds between each 10-minute bout of work. Main Outcome Measures.-Heart r ate, blood pressure, oxygen uptake, and perceived exertion during snow removal were compared with values obtained during maximal arm-ergomet er and treadmill tests. Results.-Mean heart rate during shoveling was 154 and 173 beats per minute at 2 and 10 minutes, respectively, corres ponding to 86% and 97% of maximal heart rate. Relative heart rate (per centage of maximal heart rate) during shoveling was inversely related to aerobic fitness (r= -0.65; P=.05). The highest heart rate and perce ived exertion responses during shoveling, arm-ergometer, and treadmill testing were comparable. Systolic blood pressure during snow shovelin g (198+/-17 mm Hg) was significantly greater (P<.003) than during arm ergometry or automated snow removal and slightly greater than during m aximal treadmill testing (181+/-25 mm Hg). Oxygen uptake during shovel ing was similar to that for arm ergometry (5.7 vs 6.3 metabolic equiva lents), but lower than for treadmill testing (9.3 metabolic equivalent s). Cardiorespiratory and perceived exertion responses were reduced du ring automated snow removal. Conclusion.-Heavy snow shoveling elicits myocardial and aerobic demands that rival maximal treadmill and arm-er gometer testing in sedentary men. These responses may contribute to ca rdiovascular events reported after heavy snowfalls.