Exercise as it relates to Disease/Effects of aerobic endurance and strength training in obese adults

This is a systematic review of the paper “Both aerobic endurance and strength training programs improve cardiovascular health in obese adults” by Inga E. Schjerve et al .

What is the background to this research?

The number of obese and overweight individuals has risen at an alarming rate over the last few decades. The young male (18-24) population has risen from 5.1% obese and 24% overweight to 13.8% overweight and 29.3% overweight. While the young female population (18-24) has increased from 13.2% overweight and 5.8% obese to 20.6% overweight and 20.6% obese in the same time period. . Internationally, 312 million people in 2008 were classified as being obese with a BMI (body mass index) greater than 30 and 1.1 billion people overweight with a BMI of 25-29.9 with worldwide prevalence of obesity almost tripling since 1975.The aim of this study was to look at the efficiency of moderate and high intensity level aerobic training and strength training on improving cardiovascular health in obese and overweight populations. This paper looks to answer the question “which of high-intensity aerobic exercise, moderate-intensity aerobic exercise or strength training is the optimal mode of exercise” in obese adults . This research is important due to the rapidly increasing population size. Overweight and obesity has now been not only nationally classified but also internationally as an epidemic. Due to this it is now, more than ever before, critical that research is conducted to find out the best way to safely and more efficiently slim down this population to improve national and international health. In doing so, this will reduce the additional health problems caused by obesity such as some forms of cancer, osteoarthritis, respiratory complications such as obstructive sleep apnoea and coronary heart disease.

Where is the research from?

This study was conducted in Norway, and while Norway has a lower obesity prevelence than most countries, this study is based on an epidemic that has a similar methodology of classifying obesity to most countries. The study was assisted by multiple organisations and sponsors; however, these organisations and sponsors do not have any economical investment into this study allowing there to be an un-bias lead on the research conducted or the results published

What kind of research was this?

This study was a randomised clinical trial in which subjects were randomly given a treatment method for the course of 12 weeks. The subjects were, however, encouraged to continue normal nutritional habits leaving the possibility for this data to be slightly skewed depending on whether the subjects maintained their regular eating habits or if they increased or decreased. This evidence from this study does not dramatically differ from other similar research papers but does inherently have a slight difference in results.

What did the research involve?

This research was comprised of several different procedures involving samples and tests. Each week, subjects would participate in three exercise sessions. Two of these were monitored in a lab and one was conducted in a home environment. This leaves the possibility of subjects not appropriately participating in the study program whilst at home by either not completing, not completing to the required level or exceeding the required level. These included aerobic training where subjects exposed to high intensity had a warm up period of 50-60% max HR (heart rate) with 4x4 minute intervals at 85-95% max HR with 3-minute active breaks consisting of jogging or walking at 50-60% max HR. Moderate intensity subjects were exposed to continuous walking at 60-70% max HR for 47 minutes. Subjects exposed to strength training started each session with a 15-minute treadmill work out by walking at 40-50% of max HR. This creates the possibility for some error in the overall results as the strength participants completed 45 minutes of aerobic training each week. The subjects completed four series of five repetition using a leg press machine at approximately 90% of 1RM (one maximum repetition) . Subjects also performed abdominal and back exercises of three series of 30 repetitions with 30 seconds of rest between series. In the home environment subjects walked to warm up and used either a leg press machine or squats with weighted backpacks . The procedures involved included:

• endothelial function measured as FMD (flow-mediated dilation)
• Blood profiling, where blood samples were taking after 8 hours of fasting to analyse Serum ferritin, triacylglycerols, HDL (high-density lipoprotein)-cholesterol, total cholesterol, haemoglobin, high-sensitive CRP (C-reactive protein), Na+, K+, creatinine, HbA1c (glycated haemoglobin), glucose and insulin C-peptide .
• V˙o2max, measured on a treadmill.
• Maximal leg strength using a leg press machine.
• Biochemistry of muscle biopsies to analyse protein levels.
• Skeletal muscle SERCA (sarcoplasmic/ endoplasmic reticulum Ca2+ ATPase) activity to measure maximal rate of Ca2+ into the sarcoplasmic reticulum. This was performed due to the re-uptake is inversely related to fatigue in skeletal muscle. A decreased maximal rate indicates a low aerobic capacity.
• Finally, results were analysed using a two-way ANOVA test. Combined with using Shapiro-Wilk W test to normalise the data as well as the Bonferroni post-hoc test was used to adjust results for comparison of multiple data sets. .

This research invasive but necessary for the extremely thorough and deep data that was extracted. The exact protocols that were used were identified in the paper and used with international guidelines to produce the most accurate and consistent data. The biggest limitations for this data are the self-administered exercise and nutritional factor. The data cannot be completely valid and reliable while subjects perform part of the treatment without supervision and while a key factor such as nutritional consumption in exercise-based research is left unmonitored.

What were the basic results?

• Vo2max increased in all subjects by 10, 16 and 33% in strength training, moderate-intensity and high-intensity aerobic training respectively. .
• 1RM increased by 25% for subjects exposed to strength training whereas there was no significant increase for moderate or intensive aerobic training subjects .
• PGC-1α (peroxisome-proliferator activated receptor γ co-activator 1α), There was an increased in both strength and high-intensity aerobic training for PGC-1α protein levels with moderate-intensity level intensity seeing no significant change .
• SERCA was affected in strength and high-intensity aerobic training with maximal Ca2+ increasing by 72% and 73% respectively while moderate-level aerobic again had no significant effect .
• FMD was significantly improved in all subject groups with high-intensity aerobic training having a significantly higher effect on FMD then the other two subject groups .
• Body composition was affected a small yet significant change. Body weight decreased by 3% for moderate-intensity and 2% for high-intensity aerobic training, however, strength training saw no change on body weight.

What conclusions can we take from this research?

These results definitively demonstrate the differences between the three subject groups. It highlights the body’s adaptations to various forms of exercise and the clear benefits from each of these forms. The results were so critically analysed and moderated to produce the highest quality of results from these tests to be as valid and reliable as possible. These tests clearly demonstrate that there is some correlation between the three forms of exercise and obviously show that some exercise is always better than none no matter form that it is classified under. As the title of the paper suggests, both moderate and high-intensity aerobic and strength training programs improve cardiovascular health in obese adults. This paper then does meet its aim of looking at the efficiency of moderate and high-intensity level aerobic training and strength training on improving cardiovascular health in obese and overweight populations but demonstrates that while high-intensity aerobic exercise is the optimal mode exercise, strength training is just as effective in most aspects. Papers such as “The addition of muscle strength to aerobic interval training: effects on muscle strength and body composition in CHF patients” have benefited form this study and its correlation between aerobic interval training such as the high-intensity training and strength training allowing them to base some of their research from the facts found in the paper.

Practical advice

This paper allows EPs (Exercise Physiologists) to create diversity within their programs to help individuals who are suffering from obesity, are overweight or heading to becoming overweight in order to help with participation by giving training programs some diversity or to create programs based on ability. For example, an obese person who suffers from chronic osteoarthritis may not be able to participate in high-intensity aerobic training but could participate in short duration strength training could be an alternative training method.

Research such as the paper Aerobic or Resistance Exercise, or Both, in Dieting Obese Older Adults is a continuation of the research conducted in this paper and addresses the issues related to self monitored nutritional intake that would have a significant impact on the results in this paper. It also adresses the concerns of unmonitored exercise that is assumed to be completed at a set level or completed at all.

Further information/resources

• "Both aerobic endurance and strength training programs improve cardiovascular health in obese adults” by Inga E. Schjerve et al.

• The addition of muscle strength to aerobic interval training: effects on muscle strength and body composition in CHF patients”

• Aerobic or Resistance Exercise, or Both, in Dieting Obese Older Adults

• Effects of aerobic and strength-based training on metabolic health indicators in older adults