Throughout my four years at McGill, studying kinesiology, you come across courses you just don’t like, and others you love. This past year, I took a particular interest in exercise physiology and pathophysiology. As many of you may or not know, kinesiology is a very evolving field of study, used by the vast majority of undergrad students to branch off into different professional fields. Having said that, the research and knowledge coming out of this area is really “mind blowing”. In these classes I was constantly searching articles on “PubMed” or “Google Scholar”, further researching some of the findings being presented in these courses. Naturally, I want to share some of these articles and really highlight the significance of these findings. In the following paragraphs I am going to highlight some cool research by Bjorgen et al. (2009), a study that was presented in my exercise pathophysiology class. In their study they prescribed two aerobic high intensity interval training programs, one was performed by alternating legs (single leg cycling), the other performed by using two legs simultaneously. Oh, and this was prescribed to patients with chronic obstructive pulmonary disease.
COPD diagnosis is based on a reduced FEV1/FVC value (<0.7), while severity is based on reduction in FEV1 (Image: http://www.advaceweb.com)
It is widely explored and understood in the scientific literature that COPD is a multi-organ process that’s results in poor physical activity and exercise performance due to the ventilatory restriction experienced. This restriction causes a state of dyspnea, which is understood to limit a patient’s exercise tolerance, lowering their ability to respond to a metabolic stress (i.e. activities of daily living, exercise, etc.). Additionally, it is understood within the scientific literature that a reduction in the exercising muscle mass reduces the ventilatory drive of an individual. Therefore, Bjorgen et al. (2009) tested whether a high interval training program with the reduction in muscle mass (single leg cycling) could increase the whole body peak VO2 in subjects with COPD, in comparison to two leg cycling high intensity interval training. Bjorgen et al. (2009) hypothesize that one leg high intensity cycling training will challenge the working muscles without inducing a ventilatory limit. Therefore, further hypothesizing that these individuals doing one-leg high intensity interval training will reap greater metabolic adaptations, resulting in a greater whole body VO2max training response than high intensity two-leg interval cycling.
Single Leg Cycling (Dolmage & Goldstein, 2008)
It was concluded that upon the completion of this 8-week intervention study that all patients, independent of the training group, where able to accomplish the training within the desired training range. Supporting that both modalities of high intensity interval training are feasible for COPD patients. As well, both the single leg cycling and two leg cycling interventions were found to increase the individuals’ peak whole body VO2 and work load/power output. However, the one-leg training (OLT) group improved their peak VO2 and workload/power output significantly more than the two-leg training (TLT) group, from pre to post training (Table 3). Besides these major findings, two thought-provoking findings developed from this study, concerning the groups training progressions and qualitative analysis of the patients limiting factor to training. The OLT group had a significant training progression, to the point where at the end of the study they were training at the same absolute workload as the TLT group, WITH ONE LEG (Figure 1)! Upon qualitative investigation as to what was the patients limiting factor to training, the TLT group said ventilation, while the OLT group said leg fatigue.
Table 3: Parameters Measured (Bjorgen et al., 2009)
Figure 1: Training Progression (Bjorgen et al., 2009)
These findings suggest that reducing the exercising muscle mass (OLT) stresses the individual’s muscular metabolic function to a greater degree than traditional training methods (TLT). This greater metabolic stress occurs however at a reduced ventilatory drive. This is important to such a population like COPD patients, because the patient is able to avoid entering a state of hyperinflation. Therefore, COPD patients are able to stress their muscular metabolic system enough to cause adaptations, which are greater than traditional two-leg interval training. These adaptations increase the individual’s ability to do physical activity, as their muscles are in better condition. Therefore, healthcare professions can increase their COPD patient’s quality of life and adoption to doing physical activity by using such a training protocol as seen in this study by Bjorgen et al (2009).
Bjørgen, S., Hoff, J., Husby, V. S., Høydal, M. A., Tjønna, A. E., Steinshamn, S., . . . Helgerud, J. (2009). Aerobic high intensity one and two legs interval cycling in chronic obstructive pulmonary disease: the sum of the parts is greater than the whole. European Journal of Applied Physiology,106(4), 501-507. doi:10.1007/s00421-009-1038-1
Dolmage, T. E., & Goldstein, R. S. (2008). Effects of One-Legged Exercise Training of Patients With COPD. Chest, 133(2), 370-376. doi:10.1378/chest.07-1423