Taking a 10-day break from resistance exercise re-sensitizes muscle to anabolic signaling pathways (i.e., mTOR).
WHY TAKING A BREAK FROM RESISTANCE EXERCISE CAN INCREASE MUSCLE GROWTH KEY POINTS:
- Taking a break from resistance exercise (i.e., 10 days off) re-sensitizes muscle to anabolic signaling pathways (i.e., mTOR).
- There was no difference in anabolic signaling hormones between progressive resistance exercise and constant overload.
Introduction
Lifting weights is addictive! Going to the gym gives you a great pump, improves well-being, and makes you feel better after a workout. According to a new study, I am going to say something that most people don’t want to hear….taking a break from the gym may help muscle growth. Studies have shown that muscle growth is a sequence of protein synthesis. mTOR is a master regulator of protein synthesis in muscle. (1, 2) mTOR is such a powerful regulator of protein synthesis that if you administer a drug that blocks this pathway, muscle growth will not occur. (3, 4)
For some reason, scientists have not been able to figure out is that there is a reduction in protein synthesis as resistance exercise occurs. It is well known that trained athletes have a blunted increase in protein synthesis compared to untrained athletes.(5) A previous studyobserved a decrease in mTOR four hours after a chronic resistance exercise program for acute 10 weeks compared to the initial response when subjects first started training (i.e., greater increases in mTOR). In rats, it has been found that regular resistance exercise causes desensitization of muscle anabolic response, and a brief period of inactivity can restore muscle anabolic activity.(6) Restoring the sensitivity to muscle after taking a break may re-start muscle growth.
TAKING A BREAK FROM RESISTANCE EXERCISE STUDY
Researchers examined the chronic effects of mTOR responses on anabolic activity and how taking a break and not training affected the muscle anabolic responses. They had untrained subjects assigned either a progressive or a constant overload group. Subjects in the progressive overload group added 5% more weight when over 12 repetitions were performed in the last set. The constant overload group did not change the weight over the study and performed the repetitions not exceeding 12 repetitions per set. The subjects performed 3 sets of leg extensions and 3 sets of leg presses. After 4 weeks, the subjects took a break from exercising and stopped lifting for 10 days.
REVISITING THE ANABOLIC RESPONSE: THE IMPACT OF TRAINING BREAKS
A surprising revelation from the study was the lack of difference in anabolic signaling pathways, specifically mTOR, between those who followed a periodization routine and those who stuck with a constant overload approach. Intriguingly, both groups experienced a decline in these anabolic pathways after just a week into their resistance training regimen. Yet, the plot thickens: after a 10-day hiatus from weightlifting, there was a rejuvenated sensitivity in the muscles’ anabolic responses once resistance training recommenced.
THE RECOVERY POWER OF A TRAINING BREAK: A DEEPER INSIGHT
In a recent study, researchers delved into the effects of consistent resistance training on the anabolic signaling pathways of the body. Their findings were both intriguing and enlightening. When resistance exercises were performed three times a week, there was a marked decrease in the phosphorylation of anabolic signaling proteins. This might suggest that continuous, unbroken training could potentially dampen the body’s anabolic response over time.
However, the study took an interesting turn. When participants took a 10-day break from their resistance training, their muscles displayed a renewed sensitivity to anabolic responses upon resuming their workouts. This suggests that the muscles underwent rapid structural changes during the break, preparing them for enhanced growth and recovery once training resumed.
The researchers concluded, “Consistent resistance training, especially when done thrice weekly, can lead to a reduction in the activation of anabolic signaling proteins. Yet, this can be counteracted by introducing a 10-day microcycle without any resistance exercise, pointing to the rapid adaptability of muscle fibers.” This study stands as a testament to the importance of incorporating breaks in training routines, highlighting that a short hiatus can significantly boost the body’s anabolic response to resistance exercise. (7)
REFERENCES
1. Baar K, Esser K. Phosphorylation of p70S6kcorrelates with increased skeletal muscle mass following resistance exercise. American Journal of Physiology-Cell Physiology. 1999;276(1):C120-C7.
2. Yoon M-S. mTOR as a Key Regulator in Maintaining Skeletal Muscle Mass. Frontiers in Physiology. 2017;8.
3. von Walden F, Liu C, Aurigemma N, Nader GA. mTOR signaling regulates myotube hypertrophy by modulating protein synthesis, rDNA transcription, and chromatin remodeling. Am J Physiol Cell Physiol. 2016;311(4):C663-c72.
4. Drummond MJ, Fry CS, Glynn EL, Dreyer HC, Dhanani S, Timmerman KL, et al. Rapamycin administration in humans blocks the contraction-induced increase in skeletal muscle protein synthesis. J Physiol. 2009;587(Pt 7):1535-46.
5. Kim PL, Staron RS, Phillips SM. Fasted-state skeletal muscle protein synthesis after resistance exercise is altered with training. The Journal of physiology. 2005;568(Pt 1):283-90.
6. Ogasawara R, Kobayashi K, Tsutaki A, Lee K, Abe T, Fujita S, et al. mTOR signaling response to resistance exercise is altered by chronic resistance training and detraining in skeletal muscle. J Appl Physiol (1985). 2013;114(7):934-40.
7. Jacko D, Schaaf K, Masur L, Windoffer H, Aussieker T, Schiffer T, et al. Repeated and Interrupted Resistance Exercise Induces the Desensitization and Re-Sensitization of mTOR-Related Signaling in Human Skeletal Muscle Fibers. International Journal of Molecular Sciences. 2022;23(10):5431.
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