You’ve heard the phrase “use it or lose it” and that certainly applies to strength-training. Even if you’ve worked hard to build muscle strength and definition, give the weights a break for too long and you’ll lose your hard-earned gains. Fortunately, this doesn’t happen to most dedicated fitness buffs because they train regularly. But have you ever wondered how long it takes to start losing muscle mass and strength when you stop working out? The answer may be “sooner than you think.”
What One Study Shows
In an interesting study carried out at the University of Massachusetts, researchers asked male participants to wear an elevated sole on their right foot and to use crutches to get around so only their right foot touched the ground when they walked. Their left leg, although free to move, didn’t touch the ground or bear weight and over the course of the two-day study. At the end of 48 hours, they did muscle biopsies and looked at genetic markers that might indicate atrophy in the left leg that didn’t bear weight for two days.
The results were surprising. Even after two days, the leg that didn’t contract against resistance or bear weight showed gene and protein changes consistent with early muscle atrophy. Even more surprising was the leg that didn’t work for two days didn’t return to normal quickly from a muscle protein standpoint after it started bearing weight and actively contracting again.
Does Sitting All Day Cause Muscle Breakdown?
This suggests that muscles may show early signs of atrophy after only short periods of inactivity and disuse. How short? According to this study, two days or less. This raises another question. Does sitting all day in a chair at the office without moving around trigger breakdown of lean body tissue, especially if you haven’t done significant weight-bearing exercise or resistance training for a few days? It’s an intriguing thought.
We already know that too much sitting isn’t good. Research suggests that staying glued to your chair too long during the day increases the risk of health problems like heart disease, type 2 diabetes and is linked with an increased risk of mortality. But can sitting around all day in a chair make it harder to build lean body mass too? If so, that’s another reason to get up and move around during the day – go up and down the stairs and do squats and lunges in your office at intervals. This isn’t the first study to show that muscle atrophy happens quickly when muscles aren’t actively contracted. According to a study published in Massage Today, some muscle wasting occurs in as little as three days of disuse.
What about Strength?
Another study in the Journal of Applied Physiology showed that strength drops off quickly too when a muscle doesn’t actively contract. Resistance training improves the ability of your brain to communicate with your muscles so you can recruit more muscle fibers to lift a load even before your muscles start to hypertrophy. That’s why you develop greater strength early in a training program before your muscles have had enough time to adapt and grow. When muscles aren’t contracted for a few days, some of this improvement in neuromuscular function appears to be lost.
What Does This Mean?
With any training program, consistency is important. Research suggests that loss of lean body mass and strength gains begin early at the molecular level. It’s also possible that sitting in a chair eight hours a day has some impact on muscle fibers at the cellular level and might make it harder to build lean body mass. Certainly, more research is needed to prove this, but it’s a good reason to move around more during the day and to be consistent with strength training. That doesn’t mean you shouldn’t take time off, but even on those “off” days, stay active in some capacity to keep your muscles moving.
Journal of Applied Physiology November 1, 2010 vol. 109 no. 5 1404-1415.
Massage Today. “Understanding Disuse Atrophy”
Journal of Applied Physiology 1987; 62:2168-2173.