Rest is Best
We all know that adequate rest and recovery is crucial in helping us get the best results from our training. Without it, we risk the chance of overtraining, delayed muscle growth and poor training ability due to fatigue. Aside from rest and recovery outside of the gym, rest intervals between sets are also an important factor to consider as a way to maximize the benefits and effects of your training. So with that in mind, let’s take a look at what the research says. This article will be split into two parts with part 1 looking at the science behind rest intervals and a discussion on rest intervals and its effects during day to day training.
Rest Intervals - Be Specific
Individualising your training is important to ensure that you are achieving the results you want without having to jump through hoops and doing other extraneous activities. Rest intervals are no different and should also subscribe to individualisation. Depending on whether you want strength, power, hypertrophy or endurance – you need to be fairly specific about how much rest in between sets you take.
The Science Behind Rest Intervals
So how do rest intervals affect different results from training? One commonly tested idea is that the length of rest intervals will affect our training loads, that is, the amount of time we rest between sets can influence the amount of repetitions, weight or velocity at which we perform the exercise, thereby influencing our muscular adaptations. Another common idea is that different rest intervals will affect our biochemistry and biomarkers. That is, it may affect our ability to release hormones and other compounds within our body which may affect the way our body adapts to the stresses of training.
Rest Intervals & Training
Let’s first have a look at how rest intervals can affect our day to day training. Kraemer et al1 conducted research with American Football players who had considerable experience with resistance training. What was found in that study was that 3 minutes or more of rest in between sets were able to maintain a 10 repetition max (RM) exercise. However, 1 minute of rest in between sets led to a decrease in the number of repetitions performed.
Richmond & Godard2 though found that 3-5 minutes of rest was insufficient to maintain a 12RM exercise in recreationally trained men. Similarly Willardson and Burkett3 also found that 1, 2 and 5 minute rest intervals were not enough to sustain 8RM exercises. They also used recreationally trained subjects who had trained 3 days/week for around 2-3 years. Willardson and Burkett also found that lower body exercises seemed to suffer less from the amount of rest than upper body exercises, giving rise to the idea that the lower limb has greater endurance capacity. In another study by Willardson and Burkett4, they tested 30 second, 1 and 2 minute intervals on performance of an endurance exercise (15RM). They found that the number of repetitions able to be performed each subsequent set was reduced regardless of the rest time. However, more repetitions were able to be performed with 2 minutes vs. 30 seconds
Testing a whole workout of 6 exercises rather than just 1 or 2 exercises, Miranda et al5 found that 1 minute rest intervals produced less repetitions per subsequent set of each exercise. Looking at the resting time required to regain strength, researchers Weir6 and Matuszak7 both independently tested the ability of men to perform consecutive maximal strength tests (1RM). They both found that 1 minute was substantial for the majority of subjects (~75%) to repeat the maximal exercise. Regarding rest intervals and power performance, it is important to note that power performance involves a primarily anaerobic system of energy production, or in other words; it’s dependent on the amount of muscle phosphocreatine we have. In one study, Abdessemed et al8 was able to show that 3-5 minutes rest was enough time to regenerate power in untrained men for up to 10 sets. However, 1 minute rest intervals in between sets showed a decline in power performance and a switch in energy production to use of glycogen, thus showing that 1 minute rest intervals was not sufficient enough time to regenerate muscle phosphocreatine.
Applying Rest Intervals to Training
So what can we take away from all of the above information?
- At least 3 minutes rest appears to help with endurance levels and the ability to sustain repetitions in well trained men.
- 3-5 minutes is required for recreationally trained men to perform subsequent sets of an exercise, however decreased repetitions seem almost inevitable.
- Lower limb compound exercises require less rest time in between sets than upper body compound exercises to recover.
- To maintain endurance training capacity (15 or more sets), it might be useful to lower the weights rather than take longer rest intervals.(Note: Lowering the weight to achieve whole sets may not be beneficial in achieving muscle growth as it is the load which will affect recruitment of muscle fibres and to initiate muscle damage of those muscle fibres)
- Regarding tests of maximal strength, 1 minute is sufficient for recovery, but more may be required to ensure better safety.
- In terms of power, 3-5 minutes is required to recover power by recovering muscle phosphocreatine stores.
Rest intervals are an important factor to consider when working out and depending on the results that you want, the time you spend resting in between sets will need to be changed. Of course, many of us don't have the time to spend 3-5 minutes waiting around in between sets. To maximise your time, you might consider working another muscle group during that time (ie supersets). However it is important to know that rest in between sets is still important to ensure that you're psychologically prepared and that you're breathing is under control. Stay tuned for Part 2 of this series which will look at how different rest intervals will affect hormonal changes and chronic, long term muscle adaptations.1 Kraemer WJ. 'A series of studies: the physiological basis for strength training in American football: fact over philosophy'. J Strength Cond Res 1997; 11: 131-42
2 Richmond SR, Godard MP. 'The effects of varied rest periods between sets of failure using bench press in recreationally trained men.' J Strength Cond Res 2004; 18: 846-9
3 Willardson JM, Burkett LN. 'A comparison of 3 different rest intervals on the exercise volume completed during a workout.' J Strength Cond Res 2005; 19: 23-6
4 Willardson JM, Burkett LN. 'The effect of rest interval length on the sustainability of squat and bench press repetitions.' J Strength Cond Res 2006; 20: 400-3
5 Weir JP, Wagner LL, Housh TJ. 'The effect of rest interval length on repeated maximal bench presses.' J Strength Cond Res 1994; 8: 58-60
6 Matuszak ME, Fry AC, Weiss LW, et al. 'Effect of rest interval length on repeated 1 repetition maximum back squats.' J Strength Cond Res 2003; 17: 634-7
7 Abdessemed D, Duche P, Hautier C, et al. 'Effect of recovery duration on muscular power and blood lactate during the bench press exercise.' Int J Sports Med 1999; 20: 368-73