Aerobic Exercise During the Interset Rest Period

As part of my membership with the National Strength and Conditioning Association (NSCA), I am subscribed to the Strength and Conditioning Journal that publishes research studies on varying topics from the health and fitness field.

The latest addition has a brief review on an interesting topic that has piqued my interest, especially since I am currently making my way through my mass phase. Mohamed, Cronin, and Nosaka discuss "Maximizing Hypertrophic Adaptation - Possible Contributions of Aerobic Exercise in the Interset Rest Period." In laymen's terms, the potential for increased hypertrophy (muscular growth), by using light aerobic exercise between sets rather than just 'passive' rest.

The article discusses the factors involved in hypertrophy. Progressive overload, specific repetition ranges, muscular "time under tension", as well as interset rest periods. Some research has shown that decreased rest periods increase the metabolite buildup in the working muscles and blood stream, which can further increase the affinity for hypertrophy. By using a 1:1 to 1:2 work to rest ratio, individuals can increase their blood metabolite concentrations and force their bodies to not only adapt to the training stimulus, but to increase hypertrophy gains. The one downside to this technique, however, is that as individuals increase their workload or resistance levels, insufficient rest periods can result in decreased force production.

It does not take a rocket scientist to realize that by increasing rest periods between sets, individuals can therefore increase their force output. However, rest periods should be specifically designed to target a specific training goal, no different than repetition range goals, load goals, and "time under tension" intervals. If you were to do a set of chest presses, then go eat lunch and take an hour off, when you return to do a 2nd set of the very same chest press, your body will most certainly have recovered 100% to return and produce similar force outputs. This is not only an inefficient way of working out, but it is also not beneficial for muscular gains, especially in regards to hypertrophy.

Resistance training is a high-force output style of exercise, therefore most of us would be led to believe that the anaerobic energy systems supply 100% of the energy needed. This is simply not true, as triglyceride (fats) levels have been shown to decrease in muscle cells following resistance exercise (lipolysis - utilization of lipids/fats) indicating the fact that aerobic energy systems are at least part of the energy equation.

Although the aerobic energy systems are partially at work here, majority of the force produced during resistance training comes from anaerobic energy stores. This is the primary reason for interset rest, so that the body can 'top-up' its energy stores with 60-120 seconds of rest. Mohamed, Cronin, and Nosaka have studied and discussed the theory that light aerobic exercise between sets can have a number of positive effects on the human body, increasing the affinity for strength and hypertrophic gains. They present a table with proposed benefits to various systems in the body:

Mechanical - Optimize muscle temperature for greater force and velocity output, increase elasticity of muscle for increased work output (force x distance), and improve mechanical efficiency (ratio of energy turnover and mechanical output)

Metabolic - Improves lactate clearance rate and rate of energetic repletion

Hormonal - Greater total anabolic hormone production

Neural - Increase motor unit recruitment, firing frequency, synchronization and reflex potentiation, synergistic contribution, and co-contraction of antagonist

By using very light (50-60% maximum heart rate) aerobic exercise, it is possible to increase the efficiency of rest periods, allowing great hypertrophic gains. If one is to explore this avenue, then you should aim for aerobic exercise that targets the generalized area that has been worked on. For example, if you are training your legs, and have just come off of a set of heavy back squats, some light activity on an exercise bike or jogging can elicit this benefits. Similarly, if working the upper body, using a rowing machine or arm ergometer can improve recovery and circulation to the desired muscles.

This is definitely something that I will explore on my own and test out in my own workouts as the benefits gained sound very plausible.

Sources:
http://journals.lww.com/nsca-scj/Abstract/2012/02000/Brief_Review__Maximizing_Hypertrophic.2.aspx

Photo - http://www.kalisthenixfitnessblog.com/2008_09_01_archive.html

Resistance Training 7 Step Approach - Step 5: Training Load and Repetitions

Load is the most critical part of a resistance training program. I will detail ways in which fitness professionals define and use loads in a well-rounded resistance training program.

Terminology Used to Quantify and Qualify Mechanical Work

Mechanical Work - force and displacement (distance) an object or weight is moved. A quantifiable way in which you can measure mechanical work is like in Olympic weight lifting when you multiply a weight lifted by the number of times lifted.

Load Volume (or Volume Load) - Basically a measurement of weight (units) multiplied by distance (distance units) and repetitions. To note however, that certain repetition quantities alter the quality of the work being done. For example, 1 set of 15 repetitions is not the same as 3 sets of 5 repetitions.

Relationship Between Load and Repetitions

Repetitions is and should be inversely related to the load lifted, especially when calculating correct loads for specific repetition amounts. For example, the higher the load, the lower number of reps an individual should be able to lift.

Calculating 1-repetition maximum (1RM) and 10-repetition maximum for individuals is a highly effective tool to structure a proper resistance training program. Depending on an individual's goals, their resistance exercises should remain within a specific rep range to meet such goals, which will be discussed later.

Keep in mind that an individual's 1RM (or calculated 1RM) on a weight machine may be significantly higher than doing a similar action with free weights as more synergistic muscles must be involved, potentially lowering the overall strength capacity of the user.

Below is a chart that can be used to determine 1RM based on percentages of weights lifted. There are many exceptions to this chart however based upon what muscles are being worked as well as the individual's comfort and skill level.

%1RM - # Repetitions Allowed
100 - 1
95 - 2
93 - 3
90 - 4
87 - 5
85 - 6
83 - 7
80 - 8
77 - 9
75 - 10
70 - 11
67 - 12
65 - 15

Calculating 1RM

There are few different ways you can calculate a 1RM for a specific exercise for an individual. For starters, a test can be conducted in which an individual can progress through a few "warm-up" sets and then, using a hypothetical 1RM, attempt to lift their heaviest weight possible for 1 repetition. Another way to calculate is by using the above chart to have an individual complete an exercise with a desired weight for as many repetitions as they can (preferably below 10 reps or so) to then calculate a theoretical 1RM.

When attempting an accurate 1RM test, where the individual is attempting to lift their heaviest weight for 1 repetition, a few things should be considered. First of all, only those individuals who are considered intermediate or experienced weightlifters who have a lot of experience at the specific exercise should attempt a 1RM test. Also, only power or core exercises that involve large muscle groups and multiple joints can withstand the large forces placed upon the body.

Assigning Load and Repetitions Based on the Training Goal

Once a strength and conditioning specialist has made a well-judged assessment based on an individuals needs (Step 1: Needs Analysis), as well as tested for actual and theoretical 1RM's, a training program can then be designed based upon the trainee's goals and therefore load and repetition quantities.

Generally, there are 4 main categories of resistance training goal sets.

1. "Strength" training is when an individual stays in a 1-6 rep range or so (85-100% 1RM). Strength training has minimal muscular growth, but very large potential for very strong muscles. Strength training should primarily be kept to "Core" exercises (large muscle groups, multi-joint).

2. "Hypertrophy" training is the training mode that creates the most muscular growth with added strength as well. Here, an individual should aim for a 6-12 rep range (85-70% 1RM).

3. "Endurance" training is to teach your muscles to be as fatigue-resistant as possible. Not a whole lot of strength gains are found here, nor much muscular growth, but muscular endurance training certainly has its place in training many individuals and athletes alike. Here you would want to push your repetitions higher than 12 (67% 1RM).

4. "Power" training is similar to strength training but slightly different. Due to the fact that the muscles are trying to displace (move) a weight as fast as possible, the muscles can not generate as much overall force, therefore slightly lowering the power weight goals to stay within a specific rep range. Here, you would be aiming for approximately 80% 1RM in order to stay in a 2-5 rep range.

Variation of the Training Load

Although an experienced weightlifter or athlete may mentally feel prepared to lift "heavy" 3 times a week (M,W,F), the heavy strains placed on the body can quickly lead to overtraining. Instead, a 3 day-a-week training schedule involving power and other core exercises should be split into a "heavy", "medium", and "light" day where the light day involves lifting 80% of the loads lifted on the heavy day, while maintaining the same repetition counts as the heavy day.
-Tyler Robbins
B.Sc. PTS