Effect Of Age On Descent And Ascent Speed And Bottom Time In The Diving Ama

Abstract

Ama divers of Japan depend on breath-hold diving for a living. An important factor determining the efficiency of breath-hold diving is the time spent underwater, as well as the bottom time, which is the productive part of the dive. The time lost during descent and ascent depends on diving depth, and of the speed of swimming of the individual diver. PURPOSE: To study if age affects Ama’s diver speed of swimming and resulting bottom time. METHODS: We logged the dives of 12 female Ama divers in 3 age categories: 18–32 years: young, 47–55 years mid-aged, and 75–81 years older, respectively during their seasonal summer fishing at Hegurajima Japan, involving daily 4h shifts. Time-depth loggers were attached to their waists. Time and speed of descent, ascent and bottom time of the total dive time were determined. Age comparisons were made using unpaired one-way ANOVA with Bonferroni post hoc. RESULTS: Diving performance data is presented in table 1. The velocity for descent was highest in the mid-aged category while the ascent was slowest in the young category compared to both other groups. The Mid-aged category were diving the deepest.Table 1: Mean(SD) duration, speed and depth for studied age groups. Significant difference at P≤0.05 is indicated: * = Mid-aged vs. young and older, § = Young vs. mid-aged and older.CONCLUSION: The faster descent and the greater time of the dive at the bottom of the mid-aged Ama, can be a result of more efficient duck-dive technique than in young inexperienced divers, and possibly more powerful swimming than in older divers lacking the muscle power. Descent requires efficient equalization, which could be less in young and old age groups due to technical or physiological differences. Supported by the Centrum för idrottsforskning.