Rest periods continue to be a highly debated aspect of strength training. We received some feedback concerning our last post on rest periods so here is a follow-up.
Willardson and Burkett 2005 performed a study using a squat and bench press protocol. After determining the athletes 8 rep max, they were asked to perform the greatest number of repetitions possible at this weight for 4 sets. The first group was given 1 minute rest, the 2nd 2min and the 3rd 5min. Not surprisingly, the 1min group squatted their 8rm max 22.47 times while the 5min group completed 28.80 squats- 6 more repetitions! Similarly on the bench the results were 17.13 and 25.73 respectively or a difference of 7 repetitions! This indicates that if max repetition of a fixed weight is the goal, 5 min rests are the way to go.
Similarly, Rahimi 2005 completed a comparable study in which athletes completed 4 sets of max reps of their 85% maximum in the squat with 1, 2 and 5 min rest intervals. The total volume for the 1 minute group was 4.55 while for the 5 minute group was 6.17, again supporting longer rest times for max repetitions at a given weight.
Willardson performed review of the literature in 2006 wherein he details that while for loads 50-90% of the 1RM 3-5min seems to be ideal if the goal is to increase strength or the increase the number of total repetitions, other goals may exist. When strength testing; 90-120 secs appears to be sufficient, 3 min for plyometrics (shock) training and rests of 30-60 secs for maximized hypertrophy (bodybuilding) were also discussed. Clearly, 5min rests are not the be all and end all and program design and goals need to be assessed before one simply throws 5min rests at the problem.
The need to rest stems from the body’s limited ATP-PC storage capabilities and the build-up of waste products from glycolysis. Once the fast-twitch cells empty the stored ATP-PC in the muscle cells, they must begin using muscle and liver glycogen for their fuel. This leads to the build-up of lactic acid. While lactic acid in the highly trained can provide a poor fuel source (and still, only under conditions of muscular fatigue), in the untrained, it is only a waste product and must be cleared from the muscle to ensure proper recruitment. Neurological factors such as resting tension, enhanced fiber recruitment and inter-muscular coordination also play a role in fatigue and force production but how much is still undetermined and being researched. It is well known that at elite levels, the ‘effortlessness’ that athletes produce is due to excellent biomechanics and neuromuscular coordination so this clearly has an effect.