The acute effect of mouth only breathing on time to completion, heart rate, rate of perceived exertion, blood lactate and ventilatory measures during a high-intensity shuttle run
Meir, RA, Zhao, GG, Zhou, S, Beavers, R & Davie, A 2014, 'The acute effect of mouth only breathing on time to completion, heart rate, rate of perceived exertion, blood lactate and ventilatory measures during a high-intensity shuttle run', Journal of Strength and Conditioning Research, vol. 28. no. 4, pp. 950-957.
This study investigated the effect of restricting nasal breathing during a series of 20 meter shuttle runs. Ten male participants (mean age = 21.7 ± 2.4 years, height = 1.80 ± 0.62 m, mass = 79.2 ± 10.4 kg, sum of 4 skinfolds = 54.5 ± 7.8 mm) were required to either: i) dive on the ground and complete a rolling sequence (condition = GRD), or ii) complete the shuttles while staying on their feet and tagging the line with one foot, at the end of each 20 m segment (condition = STD). The shuttle runs were completed with and without a nose clip (no clip = nc; with clip = clip) under 4 different trial conditions in a randomised order (GRDnc; GRDclip; STDnc; STDclip), requiring participants to return on 4 separate occasions separated by 5-7 days. Heart rate (HR) was recorded throughout each trial and the rate of perceived exertion (RPE) was measured at the completion of each shuttle sequence. Pre- and post-trial lactate and respiratory function measures were also recorded. General linear model with repeated measures analysis indicated that there was a significant effect for Roll (GRD > STD) (p < 0.05) but not for Clip (p > 0.05) on total time to completion in the trials. There was no significant interaction of the conditions (Roll × Clip) for RPE (p > 0.05). Similarly, there was no significant effect for blood lactate measured 3 minute post the last shuttle for Roll (p > 0.05) and Clip (p > 0.05). There was a significant main effect on HR across all 6 time points (i.e. pre, intervals 1-4 and 10 min post) (p < 0.05) and for Roll (GRD > STD) (p < 0.05), but not for Clip (p > 0.05). No significant effect of Roll or Clip was found for any of the recorded ventilation measures (p > 0.05). On the basis of these findings the use of restricted nasal breathing, while performing a high intensity shuttle sequence as a method of increasing the acute training effect on athletes, is questionable and so strength and conditioning coaches should carefully consider their rationale for using such a training strategy.