Exercise May Offer Benefits Even If Patients Don’t Lose Weight

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by Marta Figueiredo PhD |

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Supervised exercise can improve physical fitness and increase lean body mass in people with Prader-Willi syndrome (PWS), and boost bone health in pediatric patients, according to a review study.

These benefits occur even in the absence of weight and fat loss in these patients, who are less active than their non-obese peers and those with obesity not related to a specific syndrome, the study found.

The findings add to the previously reported benefits of individualized exercise programs and further support their implementation in this patient population.

The study, “Physical Activity in Patients with Prader-Willi Syndrome — A Systematic Review of Observational and Interventional Studies,” was published in the Journal of Clinical Medicine.

PWS, the most common cause of genetic obesity, is associated with hyperphagia (excessive appetite), low muscle tone, and reduced motor skills and physical fitness. The disease may also cause intellectual disability and low bone mineral density (with increased risk of fractures), which may be linked to poor physical activity. As such, patients are prone to develop obesity with severe complications, such as cardiac or respiratory failure.

While promoting physical activity is an important approach to manage PWS, “less than 10% of children with PWS reach the recommended level of PA [physical activity], and this proportion does not exceed 20% in adults,” the researchers wrote.

According to current guidelines, children are advised to engage in one hour per day of moderate-to-vigorous physical activity, and adults are to exercise 150 to 300 minutes per week (at least 30 minutes per day).

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Previous studies have reported a low level of physical activity in PWS patients, but whether this is related to obesity per se, or to PWS-associated physical and intellectual disabilities remains unclear.

Researchers in France set out to describe habitual physical activity and sedentary behavior in these patients, compared with non-obese people and those with obesity not related to a specific syndrome (non-syndromic obesity), as well as the effects of physical activity interventions in this patient population.

They reviewed studies published between January 2000 and December 2020. From the 46 studies accessed for eligibility, 25 studies, covering 395 children and adults with PWS, were included in the analysis.

Most studies were conducted in the U.S., involved children and adolescents with PWS, and included patients who had previously received or were currently on growth hormone treatment.

A total of 14 studies, including those related to five clinical trials, described the effects of eight distinct physical activity interventions. Exercise programs were commonly conducted at home, involved resistance training in five studies, and were supervised either by instructors or physiotherapists, or by parents.

The duration of the program ranged from 10 weeks to six months, and daily duration of exercise ranged from four minutes to six or more hours.

Results showed that habitual physical activity was lower in those with PWS, compared with people with normal weight or with non-syndromic obesity. Also, PWS patients appeared to spend more time in a sedentary position and less time in light-intensity physical activity than those with non-syndromic obesity.

While the reason behind these differences between PWS-related and non-syndromic obesity remain unclear, the deficit in lean body mass seen in people with PWS compared to those of similar obesity “may explain, at least in part, the lower level of PA observed in patients with PWS,” the team wrote.

The proportion of PWS patients meeting physical activity guidelines was low: between 5% and 8% in children, and between 15 and 25% in adults. However, and in contrast with previous findings, these proportions were comparable to those reported for people with non-syndromic obesity.

“This discrepancy can be explained by the fact that PA volume (e.g., daily steps) considers any intensity of PA (light, moderate, or vigorous), whereas PA guidelines are based on the amount of moderate-to-vigorous PA,” the researchers wrote.

In addition, higher habitual physical activity was associated with lean body mass in children and adults with PWS, and with improved bone health in pediatric patients alone.

These findings suggest that reaching the recommended level of at least moderate physical activity “may be particularly challenging” for people with low physical fitness such as PWS patients, and that the current guidelines should be seen “as a goal to strive for rather than a minimum level to be achieved” in this patient population, the team added.

“Promoting light-intensity PA throughout the day may be a complementary and more feasible approach that may bring substantial health benefits in patients with PWS and could represent a first step in progressing towards higher levels of PA,” the researchers wrote.

Moreover, physical activity interventions were found to effectively improve patients’ physical function (muscle strength, walking distance, and coordination) and increase their habitual physical activity, without leading to significant drops in weight and fat mass.

These exercise programs, with usually high attendance and no serious adverse events reported, were also associated with increased lean body mass and improved bone health in children with PWS.

Physical activity is likely to reinforce the effects of growth hormone therapy, and has been described as a co-adjuvant intervention to such therapy in children with this disorder, the team noted.

These findings highlight that “supervised PA programs are beneficial for children and adults with PWS,” and that “support should be provided to families to facilitate their implementation in real-life settings,” the scientists wrote.

Physical activity alone may not have a substantial effect on weight loss in PWS patients, which is consistent with what is observed in adults with non-syndromic obesity, the team noted.