The first two posts relating to this piece of research (The effects of low volume resistance training with and without advanced techniques in trained participants. Jürgen Giessing, James Fisher, James Steele, Frank Rothe, Kristin Raubold, Björn Eichmann) looked at the reasons we consider this research paper to be of value, the exercise protocols used and the differences in protocol between the three groups (ssRM, ssMMF and ssRP).
In this post, we will look at how the researchers gathered the data and the actual results of the study in detail and we will take a look at the conclusions that can be made and what this means for training ourselves and clients at a practical level.
First, let’s hear from James Fisher, one of the researchers involved in this study. James Fisher and his colleague, James Steele, visited us in London recently and spent a day with HITuni, where we had the opportunity to discuss exercise.
What outcome did the researchers expect
Prior to analyzing the data the researchers hypothesized that the Rest Pause group would see the greatest adaptations out of all three groups:
“It was hypothesised that the use of advanced techniques in low volume RT would enhance strength and body composition outcomes and that RP training would result in the greatest adaptations.”
What did the researchers actually measure?
- Strength– which was measured by way of maximal isometric tests.
- Body composition– which was measured by the use of a bioelectrical impedance testing device.
Maximal isometric strength testing was carried out twice prior to the training intervention, and twice after the training intervention. The tests were performed at least 48 hours apart each time and the researchers used the highest results attained.
The isometric strength tests were carried out on five of the same MedX exercise machines that the subjects had used during the training intervention. Specifically tests were performed for knee extension and flexion (for left and right limbs independently), for trunk flexion, chest press and elbow flexion.
The researchers were able to use these dynamic exercise machines to test for isometric strength by employing a clever portable device known as The Strength Meter.
The Strength Meter looks like an overgrown weight stack pin and it can be placed directly into a desired hole on the weight stack guide rod of an exercise machine.
This is done in the same way as if you were pinning the stack for a regular static application: so that the client can move the movement arm freely from the start position to the desired static testing position, at which point the load selected is engaged. The load used is too heavy for the client to produce any further movement, and against which a static or isometric can be performed.
Unlike a regular pin, The Strength Meter has internal strain gauges on its top and bottom sides, which effectively measure the force they are exposed to during the test and provide a read out of that force in Newtons.
The Strength Testing Protocol
Prior to the isometric test on a machine the subjects performed a warm up of 4 full range repetitions with what the researchers describe as a “light load” using a 4-2-4 rep count.
The movement arm of the machine was then locked into a specific position chosen for the isometric testing with The Strength Meter. The subject would then have one practice attempt performing an isometric contraction at 50% of perceived maximal effort.
To do this the subject moves the movement arm of the machine from the start position to it’s locked position and then commences performance of an isometric contraction by increasing force applied to the movement arm. Subjects were instructed to take around 3 seconds to reach maximal effort at which point they attempted to sustain peak effort for one second before reducing force back to zero over another three seconds.
After the moderate effort practice isometric contraction the subjects were given four attempts at producing a maximal isometric contraction (with twenty seconds rest between each attempt) and the highest of the four readings was recorded.The researchers note that an instructor was always present to supervise the subjects being tested. The instructor however was not allowed to provide verbal encouragement to the subject.
Thoughts On The Strength Testing Protocol
Some of The Positives
- Upper body, lower body and trunk strength tests were taken.
- For the limbs of the lower body, left and right sides were tested independently.
- Maximal isometric contractions can provide a truer picture of actual muscular strength as opposed to dynamic tests that unavoidably measure skill improvement along with strength.
- To stay with skill for a moment, no group performed isometric contractions as protocol during the intervention (which would have given them an unfair skill related advantage when testing came around).
- Biomechanically appropriate positions were selected for testing.
- The instructors were not allowed to provide verbal encouragement during the tests (encouragement could have skewed data).
- Peak maximal voluntary contraction has been shown to be attained in ~3 seconds, making the test times appropriate.
- The repetition of attempts (4) would have helped to ensure quality of effort and therefore the data.
- How well were the subjects restrained in the machines? Would it have been possible for them to subtly alter body position to gain a temporary leverage advantage during a test?
- Why were only these particular exercises selected? For example why weren’t hip extension or pullover tested which could have given insight into effects of the exercise interventions on the hip musculature and upper back musculature?
Body Composition Measurement
The researchers measured changes in body composition by use of a bioelectrical impedance device: the Tanita MC 180 which was used to take the following measurements:
- Body mass
- Whole body muscle and fat, mass & percentage
- Total abdominal fat
- Bone mass
- Muscle and fat mass and percentage for body segments: left and right upper and lower limbs and trunk
- Total body water
- Extra and intra cellular water
Subjects were measured on this device both before and after the training intervention and this was done on a separate day from the pre and post strength testing. The researchers report that the Tanita 180 is considered to provide readings that compare well to DXA scanning results for the measurement of total and segmental body composition in healthy adults.
Thoughts on the Body Composition Measurement Protocol
It should be noted that there is currently no single practical gold standard of measuring body composition. By far the most accurate and reproducible methods of measuring body composition currently however, are magnetic resonance imaging (MRI), computed tomography and ultrasound which are superior to all other measurement techniques (outside of cadaver analysis).
One of the benefits of the above mentioned techniques is that they are capable of accurately measuring cross-sectional area changes in muscle tissue- which would give an accurate measurement of hypertrophic gains. As the researchers themselves point out future research that includes these measurement techniques will be highly valuable.
As such the quality of the body composition data attained during this research was by and large less significant and practically useful than the strength measurements. Nevertheless some worthwhile body composition data was obtained, as we shall see.
Interpreting The Results
In this post I am going to focus on the higher quality results from the research, those which will be of most practical use. We will consider higher quality data to be data that is both statistically significant (p≤.05) and has a moderate or better Effect Size (ES) score.
Effect Size helps to account for the variance in results between subjects in a group, a moderate (0.50-0.79) or large (≥0.80) ES score suggests data that is meaningful and practically useful.
Due to this criteria we will not be talking much about the Repetition Maximum group as they showed no significant changes from before to after the intervention, or as the researchers put it:
“Results suggested low volume RT performed to self-determined RM may be insufficient to induce further strength and body composition adaptations in trained persons as evidenced by lack of significant changes and marginal ES’s for the ssRM group.”
High Quality Strength Results
As we can see from the above chart, in the main the ssMMF group and the ssRP group both produced great results. The ssMMF group produced better mean strength increases for the left and right knee extension and trunk flexion. The ssRP group produced greater mean strength increases in the left knee flexion, chest press and elbow flexion. In general the quality of the ES scores were better for the ssMMF group.
The data suggests that both of these approaches to exercise are effective for previously trained individuals, with a slight edge toward ssMMF based on the quality of the data (generally greater Effect Size scores and practical significance).
The strength data that kind of bucks the trend on the above chart is that representing the knee flexion, which shows comparatively poor mean strength increases compared to the other exercises. Even the ssRP left knee flexion which is considered significant (just!) only has a small ES score. The ssMMF left knee flexion result is shown in the chart for comparison sake but is faded due to the fact it is not considered significant.
What was it about the knee flexion exercise or the hamstring muscle group that caused a relative lack of response? Were the participants closer to their genetic peak for hamstring strength prior to the intervention, was there something lacking in the equipment or the protocols employed?
This chart simply illustrates the average relative increases in strength attained by the ssMMF and the ssRP groups. It appears that both low volume ssMMF and low volume ssRP are efficacious approaches to exercise for increased strength for adults with prior training history, with ssMMF showing strongest.
High Quality Body Composition Data
On the whole when it comes to the data gathered regarding change in body composition the quality and practical usefulness of this collected data is not as valuable as the strength data. This is likely due to the equipment used to gather the data (a bioelectrical impedence device). As mentioned earlier had MRI, computer tomography or ultrasound (or two or more of the preceding) been available to the researchers the quality and usefulness of the data would likely have been much greater.
That being said four measurements from the body composition data showed significance and practical usefulness (based on Effect Size) and all four of those were results from the ssMMF group:
1. Whole body muscle percentage
Mean change +0.96% with an ES suggesting moderate-high practical usefulness.
Muscle tissue made up a greater percentage of total body weight after the training intervention.
2. Right arm muscle mass
Mean change +0.10kg with an ES suggesting high practical usefulness.
Muscle tissue in the arm musculature increased in mass following the training intervention.
3. Left arm muscle mass
Mean change +0.08kg with an ES suggesting moderate-high practical usefulness.
Muscle tissue in the arm musculature increased in mass following the training intervention.
4. Intra cellular water
Mean change +0.4kg with an ES suggesting moderately practical usefulness.
It is likely that when intra cellular water increases protein synthesis also increases whilst at the same time protein degradation is reduced in muscle tissue. This effect would be supportive of hypertrophy, and therefore it is good to see this particularly in the ssMMF group.
It should also be noted that the ssMMF group did also produce other significant positive changes in other body composition metrics, however although those readings were significant they failed to attain a moderate or high ES score, suggesting they may be less replicable and less meaningful.
What Does the Research Tell Us?
- That a low volume, low frequency (2xpw) single set per exercise protocol can be efficacious and productive in terms of strength and hypertrophy for advanced exercisers (those with RT history).
- Degree of intensity of effort, and proximity to MMF at termination of the set may be the most important factor(s) when it comes to productive resistance training, especially for those with previous exercise history.
- The ssRP group used both a comparatively heavier load and performed a higher volume of repetitions than did the ssMMF group and yet in the main did not produce quite as good results as the ssMMF group. This suggests that load and volume play a comparatively less significant role to MMF in the stimulation of strength and hypertrophy.
- Performing low volume Rest Pause exercise to Repetition Maximum may still be a productive way to train for strength improvement. For example it could be particularly useful for individuals who dislike or struggle to exercise to MMF.
What better way to wrap this series of posts than with a recent video of James Steele, one of the researchers involved in this study, exercising to Momentary Muscular Failure.
This wraps up our trilogy of posts on this particular research study, and wraps up blog posts for 2014. Happy holidays to you all!
See you in 2015.