What Helps Prevent Muscle Atrophy During Immobilization

Which leg was immobilized?

We see many patients with muscle atrophy on their affected limb. This definitely happens after surgery where whole body or single limb immobilization may be necessary. This leads to decreased muscle size and strength.

What strategies are there to mitigate this? You may be very surpised.

20 male participants (average age 33) took part in this study (Labidi et al, 2024). All were former competitive athletes, primarily in athletics, now working as fitness coaches. 

The participants were split into 2 groups. They had 2 weeks of single lower leg immobilization with a orthopaedic walking boot . They were taught to use crutches and instructed not to weight bear on that leg. This was followed by 2 weeks of supervised rehabilitation before return to sport (RTS). 

The participants underwent 4 weeks of a standardized training program to ensure a common training base before the immobilization procedure. There were 5 sessions (3 resistance, 2 endurance) of training each week. They also received 4 nutritional sessions inclusive of face-to-face consults with a nutritionist and educational videos to standardized daily energy and protein intake throughout training, immobilization and rehabilitation phases.

Picture from SIU Med

The participants then underwent 4 weeks of supervised training. The 1st group had whole body heat therapy (HEAT) while the 2nd group had sham treatment (SHAM) throughout the immobilization and rehabilitation periods.

During the immobilization period, the participants received 11 passive interventions of 60 minutes. The HEAT group sat in a heat chamber at 48 to 50 degree celcius at 50% relative humidity (at 0 m altitude). 

During the rehabilitation period, the participants received 5 active interventions (conditioning) of 60 minutes. The HEAT group performed the sessions in the heat chamber at 35 degrees Celcius and 60 degress relative humidity at 0 m altitude. 

The SHAM group sat in an altitude chamber, set at only 200 m (to create a placebo effect while avoiding any effect of altitude). The temperature was at 24 degree celcius and 40% relative humidity.

Ready for the results? All of the following were measured pre-immobilization, post-immobilization and at RTS. Muscle strength (isometric and isokinetic) were measured. Muscle volume was measured by MRI and ultrasound while muscle biopsies were also obtained. Maximal isometric strength for the calf muscles (plantarflexion) was lower at RTS compared to pre-immobilization in SHAM. 

Isokinetic strength during a fatigue test was higher at RTS compared with pre-immobilization in HEAT but not SHAM. 

Shape of muscle and muscle thickness were lower at post-immobilization compared with pre-immobilization only in SHAM. Cross sectional area of the soleus and the medial, lateral gastrocnemius were decreased in SHAM. Only the medial gastrocnemius was smaller in cross sectional area in HEAT.

The results indicate that using heat therapy during immobilization and rehabilitation reduces muscle atrophy and maintains calf strength in healthy humans. Repeated heat exposures should be considered to counteract muscle atrophy during immobilization.

I'm not sure that it's practical to get in a sauna with a cast on but maybe with a boot or back slab that can be removed temporarily? I would do it if I wanted to return to sport badly enough or maybe if I'm old and wanted to prevent muscle bulk and strength while awaiting healing to happen. For those with with an aversion to heat, definitely no go.

Reference

Labidi M, AlhammoudM, Mtibaa K et al (2024). The Effects Of Heat Therapy During Immobilization And Rehabilitation On Muscle Atrophy And Strength Loss At Return To Sports In Healthy Humans. Orth J Sp Med. 12(10). DOI: 10.1177/23259671241281727