Exercise as it relates to Disease/Resistance training effects on hip osteoarthritis

This is a critique of the journal article titled "Effects of high-velocity resistance training on muscle function, muscle properties, and physical performance in individuals with hip osteoarthritis: a randomised controlled trial" by Fukumoto Y, Tateuchi H, Ikezoe T, Tsukagoshi R, Akiyama H, So K, Kuroda Y and Ichihashi N.

What is the background to this research?
Hip osteoarthritis (HOA) is a common joint disorder also cited as a 'degenerative' joint disease. This condition is characterised by hyaline cartilage of the joint becoming damaged which results in modifications to the joint. The cause of HOA is unknown although there are multiple factors playing a role in the generation of this condition such as injury to the joint, ageing and being overweight. Exercise is a physical form of treatment to maintain HOA, and resistance training is recommended. Resistance training is cited in numerous studies, and Fukumoto's study is one of the first to look at the comparison between velocities and resistance training.

In Australia this condition is the primary cause of hip replacements. Many individuals may experience pain and discomfort, so being able to manage this is the priority of treatment along with increasing mobility. By maintaining and preventing HOA, it helps to assist in the reduction of developing additional chronic diseases arisen from physical inactivity.

Where is the research from?
The study was undertaken at the Graduate School of Medicine at Kyoto University in Japan and was ethically approved by the Kyoto Universities ethics committee. The paper was published in the Clinical Rehabilitation journal which is a highly ranked peer-reviewed journal.

The leading author Yoshihiro Fukumoto, is a professor at the Kobe Gakuin University in Japan in the Faculty of Rehabilitation. Fukumoto has published 37 research articles which are based around muscle diseases and rehabilitation. The number of publications shown by Fukumoto may imply that his reputation in the field is not on par with other authors in the field.

The preponderance of co-authors are from Kyoto University. These co-authors had an additional range of expertise from biomechanics and HOA. With the research, conflict of interest may be evident as the study was undertaken at the same university as majority of the co-authors, meaning that they may have participated to derive their own personal benefit.

What kind of research was this?
The research conducted was a randomised controlled trial. Randomised controlled trials allow for the variable in which is being studied to be controlled by the researchers, and neutralises the risk that confounding factors will influence the overall results. This form of study is evident through various research articles when conducting interventions, as in the hierarchy of methodologies, it is seen as an effective methodology to understand an intervention, and when certifying causality it is seen as the standard criterion.

The participants of the study were blinded to which group they were being allocated to being either high-velocity or low-velocity resistance training. Although, the physical therapists which intervened the programme and the assessors were not blinded. This may have lead to the results being biased as behaviour and responses can be altered towards the measure of the subjective outcome.

What did the research involve?
Over 8 weeks, the research examined a cohort of 46 women whom had HOA either unilaterally or bi-laterally. Only women were recruited for this study due to the decrease in both physical and muscle function seen in women. A home resistance training program was designed by a physical therapist. The participants were divided into a high-velocity training group (n = 23) and a low-velocity training group (n = 23) with both groups undertaking the same exercises at different velocities. The exercises consisted of:


 * Hip abduction in supine position
 * Hip extension in prone position
 * Hip flexion in sitting position
 * Knee extension in sitting position

A theraband was used for each exercise which indicated the resistance and load. The participants performed 10 repetitions with 2 sets each. During the concentric and eccentric phases of the exercises, the low-velocity group performed these in 3 seconds per phase, whereas the high-velocity group performed the concentric phase as fast as possible, followed by a 3 second eccentric phase.

A total of 7 participants withdrew from the study; 4 from the high-velocity group and 3 from the low-velocity group. With this came one of the major limitations of the study as the number of participants involved in the study was low. This small sample size increases the chance that a type II error could have occured with the overall conclusions, which results when the hypothesis is falsely rejected due to understating the results.

To gain 100% compliance of the training program the participants had to complete the full 8 weeks of training with 56 training days total. Although, as participants had to self record their exercise, this is can be an inclusive report as people can falsely record their training. The participants were only contacted by the physical therapist every two weeks which put emphasis on participants reliance which poses as a limitation. Research articles which study resistance training effects tend to partake the training with a trainer or assessor present to reduce this limitation.

What were the basic results?
The following were key results from the study :


 * There was a significant increase in the performance of the Timed Up and Go test in the high-velocity group by 45 seconds.
 * There was a decrease in echo intensity in the gluteus maximus evident in the high-velocity group.
 * Both training groups were equal in the improvements in muscle power.
 * Muscle properties and function, physical characteristics and clinical assessment scores showed no significant difference between the groups.

Due to the small sample size of the study, the author may be underestimating the effects of the intervention. The outcome of the high-velocity groups increase in physical performance is contradicted, as the increase in physical performance is expressed through the Timed Up and Go test and not other performance tests evaluated. This means that only partial of the hypothesis is supported.

What conclusions can we take from this research?
As the study conducted had a small number of participants, further study with a more extensive sample size is needed to evaluate the difference between velocities and resistance training. It is evident that participating in either high or low-velocity resistance training can assist in strengthening muscles of the upper leg, and both forms of training are seen to be advantageous towards an individual with HOA. Overall, there were no major differences between the two groups, although on the contrary to this, if the goal is to improve physical performance, than high-velocity training may be slightly more beneficial. The increase in this performance may be based around the changing of muscle composition which is supported by various studies which emphasise muscle composition and effects on physical function.

In contemporary studies, the findings from the study correspond with research regarding resistance training and osteoarthritis, and how it provides a physical treatment method.

Practical advice
As research supports the benefits of resistance training, this form of exercise is also important in the prevention of osteoarthritis. For those unfamiliar with the Australian strength exercise recommendations please refer to: [https://www.health.gov.au/health-topics/physical-activity-and-exercise/physical-activity-and-exercise-guidelines-for-all-australians#:~:text=At%20least%2030%20minutes%20of%20moderate,most%20(preferably%20all)%20days.&text=At%20least%202%20days%20a,%2C%20strength%2C%20balance%20and%20flexibility. Physical activity and exercise guidelines for Australians]

Resistance and strengthening exercises encouraged:


 * Sit to stand
 * Standing hip flexor stretch
 * One leg balance

Other forms of exercise encouraged


 * Aerobic exercises
 * Tai Chi

It is important to note that before undergoing physical exercise that you consult with a doctor and/or physical therapist to ensure safety and wellbeing.

Further information/resources
For further information on the topic of HOA and resistance training please refer to the following:


 * Australian Institute of Health and Welfare: Osteoarthritis
 * Osteoarthritis Hip Exercises
 * Benefits of strength training