Safer mountain climbing using the climbing heartbeat index

Abstract.

As the numbers of middle-aged and elderly mountain climbers have increased with the general aging of the population, accidents during mountain climbing have increased recently. A possible cause of such accidents is an excessively difficult expedition plan. To enjoy safe mountain climbing, the plans must take account of the climber's fitness level. We developed a method to plan mountain climbing using the climbing heartbeat index (CHI). This study is based on the assumption that the work expended when climbing a mountain is equal to the potential energy of the body and load weights elevated to the height of the mountain, and that the work is proportional to the heart rate. The CHI was calculated by the following equation

$$ \hbox{CHI} = {\hbox{total number of heart beats during climbing} \over [\hbox{body weight }(\hbox{kg)} + \hbox{load weight }(\hbox{kg})] \times \hbox{altitude difference } (\hbox{m})} $$

The CHI values examined in this study (n = 94) showed very small standard deviations and were significantly correlated with the maximum oxygen uptake, V̇O_2 max (ml kg^–1 min^–1) (r = –0.934, P < 0.01); it showed a characteristic value corresponding to the fitness level in each subject. In addition, this value remained nearly unchanged even when the load was changed. Therefore, if the CHI value of an individual is known (it can be estimated from V̇O_2 max), safer mountain climbing can be planned accordingly. Once determined, this CHI value can be used repeatedly unless the fitness level of the individual changes.