BUFFALO, N.Y. -- 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 percent and underwater scuba swimming time by 66 percent,
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 percent and 26 percent, 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 December
online issue of the European Journal of Applied Physiology
and will appear in printnext month.
"Specific respiratory muscle training could allow divers in the
military, civilian rescue services, commercial enterprises and
sport to perform better underwater," said Claes E.G. Lundgren,
M.D., Ph.D., professor of physiology and biophysics in the UB
School of Medicine and Biomedical Sciences and the study's senior
David R. Pendergast, Ed.D., professor of physiology and
biophysics, adjunct professor of mechanical and aerospace
engineering and CRESE director, along with his research group, were
instrumental in the research.
Lundgren said that training the breathing muscles to improve the
performance of swimming muscles seems counter-intuitive, but is
"Typically, we think it's the muscles that move the body that
are fatigued when we tire," he noted. "However, the increased work
load of the breathing muscles is very important, particularly
underwater during prolonged or high intensity exercise such as
"As shown by other studies, when breathing muscles become
fatigued, the body switches to survival mode and "steals" blood
flow and oxygen away from the locomotor muscles and redirects it to
the respiratory muscles to enable the diver to continue breathing.
Deprived of oxygen and fuel, the locomotor muscles become
"Increasing the strength and endurance of the respiratory
muscles prevents their fatigue during sustained exercise, enabling
divers and swimmers to sustain their effort longer without tiring,"
The study involved 30 experienced male swimmers in their 20s. To
insure the safety of participants and establish uniform fitness,
all enrollees took four weeks of swim-fin and scuba-diving training
before the start of the study.
Participants also 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 four 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 four weeks, study participants repeated the
"Results showed that the RRMT and ERMT protocols used in this
study significantly extended swimming endurance through an
improvement in respiratory muscle performance," said Lundgren.
"These data are in agreement with previous studies in cyclists,
rowers and runners. They suggest that athletes in most sports could
improve their performance by undergoing respiratory muscle
training. It is also clear that the greater the stress on the
respiratory system, the larger the improvement in performance."
Lundgren noted that this type of training also may be useful for
patients who suffer from respiratory stress.
Juli A. Wylegala, Ph.D., UB clinical assistant professor of
rehabilitation sciences, is first author. Pendergast, Luc E.
Gosselin, Ph.D., associate professor of exercise and nutrition
sciences, and Dan E. Warkander, Ph.D., research assistant professor
of physiology and biophysics, are additional authors.
The research was supported by a grant from the Naval Sea Costal
Systems (Navy Experimental Diving Unit).
The University at Buffalo is a premier research-intensive
public university, the largest and most comprehensive campus in the
State University of New York. The School of Medicine and Biomedical
Sciences is one of five schools that constitute UB's Academic