How Rest Between Exercises Helps Build Muscle Strength

Summary
Strength training refers to exercises that resist muscle contraction to build muscle strength. This enhances sports performance, and the treatment and prevention of some diseases. Several variables like the number of cycles, rest and intensity can be used to customize strength training. The rest interval has proven to be critical in deciding the outcome. Hence, this review analyzes the optimization of the rest period based on the objective of the training, that is based on whether the exercise is for increasing muscle volume or stamina.

Introduction
Rest intervals between modules of strength training seem to play an important role in dictating the result. Many studies support short time intervals between exercises, while many others endorse longer time intervals for attaining better muscle strength. Contradictory findings necessitated the current review. There was a need to arrive at a consensus on suitable rest periods, depending on the desired outcome – based on whether power, endurance or volume increase was the final objective. Variations between different muscles located at different parts of the body (upper torso or lower part) were studied at rest intervals that could determine their efficacy to be trained. The hormonal changes involved in muscle function, like fluctuations in phosphocreatine, were also estimated for appropriate recovery time. However, the individual’s status (trained or untrained) as well as the goal of training (muscle volume increase or strength improvement or power enhancement) contributed in arriving at the correct rest interval.

Methodology
This review consolidated and analyzed the findings of 35 studies “addressing the rest interval between sets in strength training.” These were shortlisted from numerous Internet databases and journal searches, ensuring authentic scientific information. The review included only those studies that had a high impact on the scientific community. It was assured that the component studies dealt with the rest interval specifically, which covered all significant variable parameters.

Results
* Muscle group: The consensus was longer rest periods for upper body exercises and shorter rest for lower body exercises.
* Muscle strength: The participants training for muscle strength were able to repeat exercises more times with a two-minute rest than with a 30-second rest.
* Maximum power: It was found that a three- to five-minute rest was more efficient and safe while evaluating maximum strength (the second trial was completed by 75 percent of subjects with a one-minute rest, while 94.1 percent and 88.2 percent completed it with a three- and five-minute rest, respectively).
* Hormonal change: The one-minute rest was inadequate to regenerate lost phosphocreatine and hence, reduced power. Medium intensity with short intervals was found best for increase in growth hormone.
* In the long run, larger rest intervals were associated with better muscle strength, while it was found that with reduced intervals the oxygen usage increased.

Shortcomings
The degree of lowering resistance between cycles of training is yet to be determined. It is recommended that more studies should include numerous exercises. Alterations in muscle volume need to be considered in these calculations. The long-term effects of rest interval need further understanding and experiments. Females, people of varied physical dispositions, and the order of exercises should be assessed for input of variability.

Conclusion
This review gives an overall picture of the significance of the rest period between exercise modules and its impact on further exercising as well as its physiological implications. Although there is conflict between some authors regarding the rest period between exercise cycles, most researchers have supported a longer duration for rest. To gain better muscle power, a three- to five-minute rest was apt, while 30-60 seconds was sufficient for muscle volume increase. Really short intervals improved the muscles’ tolerance. It is not to be overlooked that the gender, the physical state of the subject, and the aim of training – all these factors combine to finally determine the rest interval for best results.

For More Information:
Rest Interval between Sets in Strength Training
Publication Journal: Sports Med, 2009
By Belmiro Freitas de Salles; Roberto Simão; State University of Rio de Janeiro and Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
*FYI Living Lab Reports Are Summaries of the Original Research.