Swimmers and scuba divers can improve their swimming endurance and breathing capacity through targeted training of the respiratory muscles, researchers at the University at Buffalo have shown.
In this pioneering work, subjects who followed a resistance-breathing training protocol (breathing load) improved their respiratory muscle strength and their snorkel swimming time by 33% and underwater scuba swimming time by 66%, compared to their baseline values.
Participants randomized to a similar protocol requiring high respiratory flow rates (endurance) improved their respiratory endurance and surface and underwater swimming times by 38% and 26%, respectively.
The group randomized to a placebo training program, conducted with the same equipment and protocol, showed no significant improvement in respiratory or swimming performance.
Results of the study, conducted in UB’s Center for Research and Education in Special Environments (CRESE) appeared in the January issue of the European Journal of Applied Physiology.
The study involved 30 experienced male swimmers in their 20s. Participants underwent baseline tests to determine pulmonary strength (maximal pressures they could generate), pulmonary endurance (time that a high ventilation could be sustained), VO2max (the maximal volume of oxygen they could consume per minute to produce energy for exercise), and length of time they could swim at a moderately high speed.
The men then were randomized to one of three training protocols: RRMT (resistance respiratory muscle training); ERMT (endurance respiratory muscle training); or PRMT (placebo respiratory muscle training). The protocols were followed for 30 minutes per day, five days a week, for four weeks.
Swimmers assigned to the RRMT inhaled and exhaled against a valve that had a set opening pressure and imposed a continuous resistance using specialized breathing valves and a computer tracking system developed in CRESE.
Swimmers in the ERMT protocol, using the same equipment, increased their breathing rate and tidal volume (total ventilation) progressively each week, while a re-breathing bag insured that the amount of carbon dioxide in the blood was held constant, in spite of the hyperventilation during the training.
During PRMT, subjects performed a series of 10-second breath-holds, with 90-second rest periods between breath-holds, using the same equipment as in RRMT and ERMT. The rest periods were shortened by 10 seconds each week, ending with a 60-second rest between breath-holds during the fourth week.
All subjects participated in a twice-a-week, identical fin-swimming maintenance program during the 4 weeks of RMT training to insure that they maintained, but didn’t increase, their fitness levels during the study’s training protocol.
At the end of the 4 weeks, study participants repeated the baseline tests.
“Results showed that the RRMT and ERMT protocols used in this study significantly extended swimming endurance through an improvement in respiratory muscle performance,” said Claes E.G. Lundgren, MD, PhD, professor of physiology and biophysics in the UB School of Medicine and Biomedical Sciences and the study’s senior author.
Lundgren also noted that this type of training also might be useful for patients who suffer from respiratory stress.