01.Mind your back
People who use weight machines and do stretching exercises are at higher risk of developing lower back pain than those who don’t, according to new research.
The study, which was published in the Journal of Science and Medicine in Sport, was conducted among 4610 white collar workers in the US aged 20-81 who were followed for almost five years. None had lower back pain at the start of the study.
Participants were questioned about the types of exercise activities they did, including different types of weight training (using weight machines, free weights or calisthenics), aerobic training and flexibility training (stretching, calisthenics, exercise classes and yoga). Those who used weight machines and did ‘stretching’ were more likely to report lower back pain at some point within the study period.
Australian National Physical Activity Guidelines recommend adults do muscle strengthening exercises at least two days per week. The UK, Canada and United States have similar guidelines and also recommend flexibility training.
But as lead author Dr Robert Sandler points out, “Given that between 70 and 90 percent of Australians will suffer from lower back pain at some point in their lives, it’s important to be aware of how to minimise the risk where possible.”
The study has a number of limitations, especially with regard to the exact type and amount of weight training and stretching involved. In terms of weight training, for example, the machines used and muscles exercised aren’t known, while types, length and frequency of stretches weren’t recorded.
However, there are plausible explanations as to how these types of exercises could cause lower back pain:
- Weight machines tend to focus on particular muscles, while free weights require the use of back and abdominal stabiliser muscles as well as the target muscles. Weight machines allow the user to lift heavier weights, meaning the target muscles develop more relative to the stabiliser muscles. Weakness of the trunk muscles, disproportional to surrounding muscles, can lead to back pain. Poor technique may also be a factor.
- Stretching can cause cellular damage in muscle tissue, which may lead to back pain. Also, overstretching beyond normal range of motion may increase pain tolerance and allow repeated, potentially damaging movement outside this range.
“Our study suggests that people should incorporate a variety of exercises into their physical training program rather than exclusively stretching or using weight machines,” Dr Sandler said.
“By supplementing weight machine training with free weights, and combining stretching with other flexibility exercises such as calisthenics or other exercise classes, the risk of developing lower back pain may be reduced.”