Five-week Respiratory Muscle Training Program Effects on Lung Function and Air Consumption in SCUBA Divers

Purpose

To test the effects of a 5-wk, bi-directional respiratory muscle training (RMT) program on the lung function and underwater air consumption of recreational SCUBA divers.

Methods

12 adults (7 men, 5 women) from the local diving community volunteered and gave written consent. Inclusion criteria were age (min. 18 yr), diving certification level (min. Open Water) and freedom from medical conditions precluding participation in submaximal testing and underwater drills.

Participants in this double-blind study were randomly assigned to either the treatment (T; n = 7) or control (C; n = 5) group. T received bi-directional RMT devices while C received shams; all were instructed to follow manufacturer’s instructions (3 sets of 10 breaths twice daily) for 5 wk. Regular activity was to be maintained throughout the study.

12 Participants

Diving Experience: from 2 months to 17 years.

Number of Dives per Year: from 5 to 100

7 in the Treatment (T) Group
5 in the Control (C) Group
No significant difference between groups for height, weight, age, diving experience, and diving frequency.

Pre- and post-tests included: total lung capacity (TLC), vital capacity (VC), residual volume (RV), YMCA cycle ergometry, and 30-min underwater drill for SCUBA air consumption (UAC) in a controlled environment.

Pre and Post Tests Performed
Pulmonary Function Testing

  • Residual Volume
  • Total Lung Capacity
  • Vital Capacity
  • Average of two trials within 0.1L for all lung volume measurements

Cardiorespiratory Testing

  • YMCA Submaximal Protocol
  • VO2max Measured in ml/kg/min

Underwater Air Consumption Drill (UAC)

  • 30 min SCUBA Swim underwater (pool)
  • Air consumption was measured in pounds per square inch (PSI)

No significant difference between groups
for variables of interest at baseline.

Statistics

An independent t-test was used to assess the demographic and dive history similarity of the two groups. A 2 (pre vs. post) x 2 (group) repeated-measures ANOVA was run for each variable of interest to investigate training efficacy between and within the groups. SPSS-PC v10 was used for all analyses; significance was set at p < .05.

Pre- and post-test pulmonary, cardiorespiratory, and air consumption values by group.

T = Treatment Group; n = 7
C = Control Group, n = 5
an = 6; bn = 4; cN = 10

Characteristic Group Mean SD
VC(L) T (pre) 4.42 1.19
(post) 4.66 1.12
TLC(L) T (pre) 5.82 1.50
(post) 6.61 1.58
TV(L) T (pre) 1.42 0.46
(post) 1.95 0.68
Air Consumed (psi) T (pre) 1057.14 257.28
(post) 683.33 183.48

The Test Group improved more than the Control Group for:
Total Lung Capacity

Vital Capacity

Residual Volume

Estimated VO2max

Underwater Air Consumption

There were significant main effects for Total Lung Capacity and Residual Volume (p > .05).

There were no significant interaction effects.

Results

The groups were similar in age (T: 25.6 ± 11.1; C: 25.0 ± 12.3 yr), ht (T: 172.4 ± 5.9; C: 179.2 ± 7.5 cm), wt (T: 80.6 ± 28.4; C: 91.2 ± 23.2 kg), diving experience (T: 3.3 ± 3.4; C: 7.1 ± 6.1 yr), and current year’s diving frequency (T: 37.3 ± 34.7; C: 41.3 ± 27.8 dives); p > .05.

Discussion

5 wks of RMT significantly altered TLC and RV but not VC, submaximal aerobic capacity or air consumption during a 30-min SCUBA fin kick drill in this small, diverse sample of recreational divers.

Although not statistically significant the improvement in UAC following RMT may be practically significant as it may increase a diver’s "bottom time".

Conclusion

Bi-directional RMT improved HR response to submaximal leg exercise (cycling), VC, as well as the amount of air consumed during a 30-min fin kicking drill. The improvement in SCUBA air consumption following RMT, though statistically insignificant for our small sample, may be practically significant in terms of extending bottom time for shallow dives where the volume of air in the diver’s SCUBA tank is usually the limiting factor for the dive.

In this study, participants using PowerLung for 3 sets of 10 breaths twice a day showed improved:
Heart Rate Response during a cycling test.

Vital Capacity

Air Consumption during a 3 minute fin kicking drill.