Short-Term Lower Body Resistance Training Improves Cardiopulmonary Capacity in Sedentary Middle-Aged Females

Research Team Members: Chad Wagoner, Erik Hanson, Eric Ryan, Ryan Brooks, Jordan Lee, Erin Coffman, Claudio Battaglini

Under the direction of Dr. Claudio Battaglini

Why did you do this study?

Maximal oxygen uptake (VO2max) assessed via a graded cardiopulmonary exercise test (CPET) on a treadmill or cycle ergometer is viewed as the “Gold Standard” among exercise physiologists in assessing an individual’s cardiopulmonary capacity. VO2max has many implications as it is indicative of one’s overall physical fitness level, and lower values are often associated with diseases and all cause mortality. Most recently, the results of a CPET have been shown to be a strong independent predictor of survival in certain cancers (i.e. Non-small cell lung cancer, bone marrow transplant, and breast cancer) that may complement traditional markers of prognosis to improve risk stratification and prognostication. In breast cancer patients, a CPET often occurs on a cycle ergometer as opposed to a treadmill in order to reduce the risk of falls stemming from treatment related balance issues and peripheral neuropathy. Previous research has cited limitations in older, sedentary, and cancer populations when completing a CPET on a cycle ergometer. Most commonly, associations among lower limb strength and VO2max values have been reported. This potentially indicates an inability to produce the required amount of strength to withstand the resistance in pedals resulting in prematurely terminating the CPET. The resulting VO2max value may not be truly indicative of the individual’s cardiopulmonary capacity. Therefore, more research is needed to explore the relationship between lower limb strength and the determination of maximum cardiopulmonary capacity. By doing so, the precision of assessing cardiopulmonary capacity can be improved in those with reduced lower limb muscular function.

Previous research has examined the impact of resistance training on cardiopulmonary capacity in many different populations ranging from healthy populations to those that have been diagnosed with cancer. However, for certain populations, the results can be doubtful and controversy is often discussed among the exercise physiology community. Overall conclusions are that resistance training may have a positive influence on cardiopulmonary capacity, even more so when using cycle ergometry on those who are either sedentary or have no experience with cycling. Most of the studies to date that have examined the effects of resistance training on cardiopulmonary capacity used training protocols lasting from 5 weeks up to 6 months. Protocols of this length limit the practical application in a clinical setting, where a precise assessment is needed quickly, often within a week of hospitalization or at the beginning of a clinical trial. Further, previous literature has shown that in sedentary populations, strength gains in response to a resistance training program can be attained as early as 2 weeks; improvements that are mainly attributed to neuromuscular adaptations. Nevertheless, these neuromuscular adaptations can in turn allow for individuals to produce greater force during the CPET, thus attaining a higher and potentially a more precise characterization of their “true” cardiopulmonary capacity. To our knowledge, no other study has examined the relationship of resistance training’s impact on cardiopulmonary capacity over such short period of training (2 microcycles) in sedentary middle-aged women. The premise of this study was to evaluate a population of women who are of similar age and fitness level of those women who are often diagnosed with breast cancer. Therefore, the purpose of this study was to examine the impact that a microcycle of two weeks of resistance training had on VO2max in sedentary middle-aged females.

What did you do and what did you find in this study?

Initially, participants underwent a screening for participation in a maximal CPET and strength testing. After the approval from a cardiologist, all participants were familiarized with all testing procedures. We then proceeded to measure maximal cardiopulmonary capacity on a cycle ergometer and lower limb strength on an isokinetic dynamometer in 25 sedentary middle-age females within 1 week of familiarization and after the 2 weeks of lower body resistance training.

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Those who were in the intervention arm completed 2 weeks of lower body resistance training (6 total sessions) consisting of leg press, leg extension, and leg curl exercises. Training loads for the 2 weeks of resistance training were determined by completing a 1-Repetition Maximum (1-RM) for the exercises listed above. Training loads for each visit can be seen in the table below. Those in the control group were asked to not change their current activity level or diet throughout the same time period.

Training Program Visits 1 & 2 Visits 3 & 4 Visits 5 & 6
Load (% 1RM) 65% 1-RM 10% increase from previous load 10% increase from previous load
Reps X Sets 2 X 10-15 2 X 10-15 2 X 8-10

Participants who completed the 2 weeks of lower body resistance training exhibited overall greater strength gains in the lower limbs as well as significantly improving their cardiopulmonary capacity.

Mean Change Scores
Variable Intervention Control
VO2max (ml/kg/min) + 2.1 ml/kg/min -1.9 ml/kg/min
Lower Limb Strength (Nm) +6.0 Nm -1.2 Nm

How do these findings impact the public?

These preliminary findings suggest that that 2 weeks of lower body resistance training can improve leg extensor strength in sedentary middle-aged women, providing them with better preparation to perform a CPET on a cycle ergometer; therefore, a more precise measurement of their cardiorespiratory capacity can be obtained. Clinicians and practitioners will in turn be able to interpret CPET data with greater confidence in regards to the individual’s health status and fitness level. Further, the data can be utilized to design training protocols with greater accuracy in this population, allowing for optimal adaptations to aerobic exercise. Compared to previous research that utilized longer training protocols, our results displayed similar responses in cardiopulmonary values in response to resistance training, however, in a much shorter time period (2-weeks). Future research should implement randomized controlled designs in order to confirm or refute these initial results as well as use this design to test other populations such as cancer patients or any other population that suffers from muscular weakness or generalized physical de-conditioning.

 

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