Effects of dynamic, static and combined work on heart rate and oxygen consumption.

The effects upon heart rate and oxygen consumption of muscular exercises including simultaneous dynamic and static contractions were studied in three male subjects. Dynamic work consisted of walking at four speeds (0·56, 0·83, 1·11, 1·39 m s−) on a horizontal treadmill; static work consisted of pushing against, pulling and holding 6, 9, 12, 18 and 24 kg; combined work associated walking with each one of the forms of static work. Physiological load is expressed in terms of cardiac cost (ΔHR) and oxygen cost (Δ[Vdot]o2). The physiological cost of combined work increases with both the walking speed and the static load. For each parameter (HR and [Vdot]o2) the extra-cost of combined work has been determined by computing the difference between the cost of combined work and the sum of the costs observed during static and dynamic exercises separately performed. The paired t-test shows significant differences for all of the walking-pushing tests, but only for 8 pulling tests and 2 holding tests. Linear relationsh...