Juhani Smolander

Work ability, physical activity, and cardiorespiratory fitness : 2-year results from project Active

An adequate level of physical activity may maintain or promote work ability in aging workers. Project Active is a randomized trial comparing a Lifestyle physical activity program with a Structured exercise program in sedentary but healthy adults aged 35 to 60 years. Subjects in both groups received 6 months of intensive intervention followed by 18 months of active follow-up. The total number of subjects was 235, from which 80 subjects participated in the work ability assessment. Primary outcome measures were energy expenditure (kcal · kg−1 · day−1), cardiorespiratory fitness (peak oxygen uptake in ml · min−1 · kg−1), and the Work Ability Index. At 6 months, daily energy expenditure had increased significantly over baseline (mean ± SD, from 33.0 ± 0.9 to 34.4 ± 1.8 kcal · kg−1 · day−1) and was maintained over baseline at 24 months (34.0 ± 2.5 kcal · kg−1 · day−1). The significant increase in energy expenditure was observed particularly in moderate levels of activity. The average percentage of body fat was significantly higher at baseline compared with 6 months and 24 months. Peak oxygen uptake increased from baseline significantly during the first 6 months (from 29.6 ± 5.7 to 30.6 ± 6.3 ml · min−1 · kg−1) and decreased to the baseline level (29.1 ± 5.5 ml · min−1 · kg−1) at 24 months. At baseline, the average Work Ability Index was 44.2 ± 4.0, and it remained unchanged at 6 months (44.4 ± 3.9) and at 24 months (44.2 ± 3.1). In conclusion, a 2-year physical activity intervention increased daily energy expenditure, reduced body fat, and maintained peak oxygen uptake in healthy, middle-aged, sedentary subjects. The average Work Ability Index score at baseline was excellent and did not change during the 2-year physical activity interventions.

Prediction of acceptable physical work loads based on responses to prolonged arm and leg exercise

Nine healthy men (aged 54-59 years) performed arm crank and leg cycle exercises for 30 min at relative work loads of 50 and 75% of peak oxygen uptake (VO2) for the corresponding muscle group, and for 60 min at a relative work load of 30% of peak VO2 for the corresponding muscle group. In the tests, heart rate (HR), blood pressure, gas exchange variables, rating of perceived exertion (RPE) and blood lactate were measured. At the 75% target exercise level, four subjects interrupted the arm-cranking test, and one subject interrupted the leg-cycle test. Owing to differences in peak values during arm-cranking and leg-cycling, the work load and the VO2 were higher during leg-cycling than during arm-cranking. There was no difference in HR between the work modes, but the HR increased to a greater extent during arm-cranking compared to leg-cycling at the 30% (NS) and 50% (P < 0.05) exercise levels. Similarly, the RPE increased more during arm-cranking compared to leg-cycling at each exercise level. The blood lactate concentration was higher after arm-cranking than after leg-cycling; at the 50% exercise level the difference was statistically significant. The results indicate a higher physiological strain with time during arm exercise than during leg exercise at the same muscle group-specific relative work load. The acceptable physical work load, expressed as the percentage peak VO2 for the corresponding muscle group, should thus be lower during arm exercise than during leg exercise. The RPE and the relative HR, expressed as percentage of peak HR for the corresponding muscle group, however, seem to be comparable indicators for the physiological strain during arm and leg exercise.

Maximal working times with a self-contained breathing apparatus

The effects of a self-contained breathing apparatus (SCBA, total weight of 15·5 kg) on relative aerobic strain (%[Vdot]O2max) and heart rate (HR) were studied at light, moderate, and heavy exercise levels on a treadmill in temperate conditions. The subjects comprised 13 firemen whose mean [Vdot]O2 max was 4·161 min−1 (range 2·85 to 5·331 min−1). Maximal working times (WTmax) with SCBA were calculated with the results for this study and with experimental data from the literature. The subjects %[Vdot]O2 max and HR increased significantly more with SCBA than in the control test without SCBA. This increase reduced the calculated WT max values. During moderately heavy exercise ([Vdot]O2control = 2·01 min−1), carrying SCBA increased the subjects %[Vdot]O2max from 48 to 69 and decreased their estimated WT max from over 60 to 44 min. The estimated WT max for a single operation with SCBA was critically short (18 min) when the average [Vdot]O2 max for men aged 20–29 (3·51 min−1) was used in the calculations. Ther...

Cardiorespiratory and thermal effects of wearing gas protective clothing

SummarySix healthy men aged 25 to 37 walked on a treadmill at work levels of 21 and 41% of their n

Responses of young and older men during prolonged exercise in dry and humid heat

dot V_{{text{O}}_{{text{2max}}} }

Physiological Strain in Work with Gas Protective Clothing at Low Ambient Temperature

n for 25 to 30 min wearing gas protective clothing (GPC) consisting of an impermeable suit with a self-contained breathing apparatus (total weight 25 kg) or shorts (control tests, CT) in a temperate environment (ta 24.3°C ± 1.0°C, rh 30–50%). When the GPC was worn at 21 and 41% n

Laser-Doppler and plethysmographic skin blood flow during exercise and during acute heat stress in the sauna

dot V_{{text{O}}_{{text{2max}}} }