PHYSICAL WORKLOAD, PERCEIVED EXERTION, AND OUTPUT OF CUT WOOD AS RELATED TO AGE IN MOTOR MANUAL CUTTING

Physical workload, output of cut wood, and perceived exertion were stu died among 15 younger (mean age 29 years) and 16 older (mean age 59 ye ars) lumberjacks, using a chainsaw and paid on a piece-rate basis. Oxy gen consumption was measured with portable equipment, while heart rate was measured telemetrically. The oxygen consumption for all working p hases was 1.8+/-0.2 l/min (means+/-SD) (younger) and 1.5+/-0.2 l/min ( older), which corresponded to 49+/-4% and 53+/-7% of maximal oxygen co nsumption estimated in ergometer bicycle exercise test. A negative rel ationship was found between relative oxygen consumption at work and ma ximal oxygen consumption (ml/kg/min). Mean heart rates for all working phases were 138+/-10 beats/min (younger) and 126+/-17 (older). The he art rate differed between the working phases, and was significantly hi gher for both groups during bunching than during the other operations. The output of cut wood did not differ significantly between the group s. Slight but significantly relationships were found between output of cut wood and maximal oxygen consumption (ml/kg/min) and oxygen consum ption (ml/kg/min) during work. Rating of perceived exertion (RPE) and simultaneous heart rate recordings during cycle tests and field studie s showed significant correlations between heart rate and RPE values du ring cycling in both groups. RPE values and heart rate in the field sh owed a slight correlation (younger) and not at all (older).