Relevant Research

in the Field of Strength Training and Sports #17/18

Written by: Joachim Bartoll, August to October 2016
Classic Muscle Newsletter, September/October 2016


Please note: This is an excerpt of only six selected studies covered in issue 17 and 18. 


In this ongoing series, I will summarize recent and relevant studies within our field of Strength and Performance Sports – including topics such as Strength Training, Hypertrophy, Nutrition, Weight Loss and more. I will wade through all the new published research and pick out the gems – so you don’t have to. If warranted, I will also add my opinion on the findings and/or the methodology of the study. No matter if you’re an Athlete, a Coach or a Personal Trainer, this series will keep you up to date with the latest research in a manageable and easily accessible way.

Muscle Growth Occur Later On in a Resistance Training Program

Muscle hypertrophy occurs in response to resistance training and consumption of protein (with more than 2 to 3 grams l-leucine. It is thought that this process of muscle growth occurs by way of an alteration in the balance between muscle protein synthesis and muscle protein breakdown over a sustained period of time.
In this study the researchers wanted to investigate how muscle hypertrophy is modulated through resistance training by assessing muscle protein synthesis (MPS) rates, direct markers of muscle damage, indirect markers of muscle damage, delayed onset muscle soreness (DOMS), creatine kinase levels, and changes in muscle fiber size at 3 separate points in a long-term strength training program.

The design

For this study, 10 young males, aged 27 ± 1 years, were recruited. All subjects performed lower body strength training for 10 weeks. These involved 2 workouts per week. Each workout comprised the bilateral 45-degree leg press and bilateral knee extension, for 3 sets of 9 to 12 repetitions per set taken to muscular failure.

The findings

Effects on muscle protein synthesis: MPS rates increased at both 24 hours and 48 hours post-exercise at baseline, but only at 24 hours post exercise at 3 weeks and at 10 weeks.
The increases were always greater at 24 hours than at 48 hours post-exercise. The increases in integrated MPS rates over each 48-hour period were greater at baseline than at 3 weeks or 10 weeks, but integrated MPS rates were similar between 3 and 10 weeks.

Effects on muscle damage: muscle damage was higher during the post-exercise recovery period at baseline, compared to at 3 weeks and at 10 weeks.

Correlations with hypertrophy: the post-exercise increase in integrated MPS rates over the 48-hour period at 10 weeks was strongly correlated (r = 0.91) with muscle fiber hypertrophy at 10 weeks, and moderately correlated at 3 weeks (r = 0.69) but there was obviously no such relationship at baseline.

The conclusion

The researchers concluded that early bouts of strength training lead to large increases in MPS rates, but they did not seem to impose hypertrophy. They theorized that the increases in MPS may rather be directed towards the repair of muscle damage than building new muscle tissue. They also concluded that the MPS response after strength training later in a program are very closely associated with increases in muscle size.

My thoughts

I’ve written tons about this. As you start a program, or shift to a new program with different stimulus, the initial gains are mostly from neurological adaptations. Our bodies always seek to adapt in the most energy efficient way possible – and that is by increasing your neurological efficiency, i.e. by increasing intermuscular coordination, intramuscular coordination, high threshold motor unit activation, muscle fiber rate coding, etcetera. The actual remodeling of muscle tissue is a very costly process and our bodies does not switch to building muscle until the neurological adaptions are optimized.
This is what is shown in this study. The conclusion by the research team indicates a lack of understanding of how the body works and how adaption occurs.
The take home message is what I’ve always preached: never stop or change a program once the initial strength gains diminishes. That is the point in your program where your body is switching from stimulating mainly neural gains to stimulating muscle growth in order to adapt and meet the challenge you put on it. Since muscle growth takes more time, gaining strength will also be slower. This is at it should be. However, if you keep switching programs or exercises, you will never experience optimal muscle growth.

Resistance training-induced changes in integrated myofibrillar protein synthesis are related to hypertrophy only after attenuation of muscle damage.
Damas, Phillips, Libardi, Vechin, Lixandrão, Jannig, Tricoli.
The Journal of Physiology. DOI: 10.1113/JP272472. 9 July 2016.

Differences in high- and low load weight training within a daily undulating periodization program

Recent research has shown that while strength is maximized by training using heavier loads, training with both high and low loads can achieve similar levels of muscle growth. Some researchers have therefore suggested that there may be fiber-type specific gains in muscle size, where low loads bring about larger gains in muscle size in type I fibers, and high loads bring about larger gains in the muscle size of type II fibers, although this remains to be demonstrated. If shown to be accurate, training with both high and low loads could be optimal.

With this study, the researchers wanted to compare the effects of high- and low load strength training, within the context of a daily undulating periodization (DUP) program, on changes in muscle strength, size, and endurance.

The design

The team recruited 16 males aged 23 ± 3 years and allocated them into either a high-load group (8 subjects) or a low-load group (8 subjects). All subjects had >2 years of resistance training experience with at least a 1RM back squat of 1.25 times bodyweight, and a 1RM bench press of >1.0 times bodyweight.
Strength was assessed by changes in squat 1RM and bench press 1RM. Muscle size was measured by reference to muscle thickness of the chest and quadriceps (lateral middle, lateral distal, and anterior), using ultrasound. Muscular endurance was measured by repetitions to failure on the squat and bench press at 60% of 1RM.
All subjects trained 3 times per week for 8 weeks, using a DUP program format. Each week, the high-load group performed 3 different workouts: 8 x 6 reps with 80% of 1RM; 9 x 4 reps with 85% of 1RM; and 10 x 2 reps with 85% of 1RM.
The low-load group similarly performed 3 different workouts: 4 x 12 reps with 60% of 1RM; 4 x 10 reps with 65% of 1RM; and 5 x 8 reps with 70% of 1RM.

The findings

Effects on strength and endurance: both groups increased 1RM squat and 1RM bench press, but there were no significant differences between the groups. The high-load group improved 1RM squat and 1RM bench press by 11.11% and 9.71%. The low-load group improved by slightly less at 10.17% and 8.98%. There was no change in muscle endurance for either group.

Effects on muscle size gains: both groups increased chest muscle thickness, as well as quadriceps muscle thickness (lateral distal, and anterior only). There were no significant differences between the groups. The high-load group improved chest muscle thickness, quadriceps lateral distal muscle thickness, and quadriceps muscle thickness by 15.24%, 18.96% and 9.85%. The low-load group improved by 12.72%, 14.32%, and 13.73%.

The conclusion

The researchers concluded that in males with strength training experience, changes in strength, muscle size and muscle endurance happen independently of repetition range, within the context of a volume-equated DUP training program.

My thoughts

Since the males had trained for a couple of years, a study over only 8 weeks are very short and does not really provide a clear picture on what is going on. A minimum of 12 to 16 weeks would have been much more appropriate. Also, relatively few measurements were taken, so it is unclear whether the training programs produced different effects on absolute strength (measured by maximum voluntary isometric contraction force), rate of force development, involuntary force production, or muscle activation.

Although the study only lasted 8 weeks, it’s a little bit interesting that the high-load group gained a little more thickness in the chest and quadriceps lateral distal area, while the low-load group gained a little more thickness in the rest of the quadriceps. This could strengthen the fact that a part of muscle gain is connected to muscle fiber types, as chest, shoulders and triceps usually are comprised of more fast twitch muscle fibers, while the quadriceps tend to be more mixed.

Volume-equated high- and low-repetition daily undulating programming strategies produce similar hypertrophy and strength adaptations.
Klemp A, et al.
Appl Physiol Nutr Metab. 2016 Jul; 41(7):699-705. doi: 10.1139/apnm-2015-0707.

Genetic muscle fiber distribution and personalized resistance training

While many genetic markers can be changed during a child’s first years, and some can be altered even as an adult, our muscle fiber distribution are a lot more difficult to impact and it can take a long time to make small changes from the style of training you do by influencing cross-over type muscle fibers.
The difference in muscle fiber setup and distribution are a big part in explaining why some people do better than others on the same training program. Other factors include limb leverages, hormonal status, internal and external stress factors, nutrient status, training effort, and recovery abilities.

In this study, the researcher’s objective was to test a method of predicting the development potential of explosive power and aerobic endurance qualities in response to either high load (low repetition) or low load (high repetition) strength training, using a panel of 15 gene polymorphisms.

The design

They set up two different studies. In Study 1, 28 Caucasian male University athletes, all aged 18-20 years successfully completed it.
In study 2, 39 male soccer players, all aged 16-19 years successfully completed it.
All athletes completed an 8-week high- or low-load resistance training program, which was either matched or mismatched with their individual genotype. It was assumed that athletes with a genetic propensity for power development would benefit to a greater extent from high load (low repetition) training while athletes with a genetic propensity for endurance development would benefit more from low load (high repetition) training. The high load group trained using 10 sets of 2 reps, while the low load group trained using 3 sets of 10 to 20 reps. The participants transitioned from their normal training plan to the designed 8-week intervention followed by an eight-week wash-out period.

Explosive power was assessed by the countermovement jump (CMJ). Aerobic endurance was assessed by reference to the 3-minute cycle ergometer test. Gene analysis was performed by taking saliva samples, which were then analyzed by an algorithm (the DNAFit Peak Performance Algorithm) to determine percentage power vs. endurance ratio (P/E). Each allele relating to power or endurance was scored with a number of points (0, 1, 2, 3 or 4) according to the expected effect of the polymorphism on power or endurance ability, respectively.

The findings

Effects of high and low load training: combining both cohorts, there was no difference in the effects of high load and low load training on CMJ (5.4 ± 5.0 vs. 4.6 ± 6.1%) or on the 3-minute cycle test performance (4.3 ± 3.8 vs. 4.3 ± 3.7%).

Effects of genotype on response to training: there was an interaction effect of genotype on the response to training. Using high load training, athletes with the power genotype improved CMJ and 3-minute cycle test by 7.1 ± 5.9% and 6.5 ± 2.9% but using low load training, they improved CMJ and 3-minute cycle test by only 2.3 ± 4.8% and 1.8 ± 2.8%.
Similarly, using high load training, athletes with the endurance genotype improved CMJ and 3-minute cycle test by 2.8 ± 5.7% and 2.6 ± 3.3% but using low load training, they improved CMJ and 3-minute cycle test by 7.6 ± 4.0% and 6.0 ± 3.5%.

The conclusion

The researchers concluded that matching an athletes' genotype to either high load or low load training may be a powerful tool to aid more personalized, and precise, resistance training prescription in the future.

My thoughts

The limitation of this study is that they only tested the effect of altering the relative load used, while other training variables were not explored. While load is one of the biggest factors between fast twitch and slow twitch muscle fibers, other factors such as explosiveness, acceleration, rest periods, total volume, etcetera, are also very important.
And as some of you probably know, I’ve been basing some of my training principles on this for +10 years – utilizing a higher frequency for explosive muscles like the shoulders and triceps, while using a higher volume but lower frequency for stabilizing and pulling muscles such as the latissimus and biceps.
It would be interesting with similar studies on hypertrophy and the idea to train body parts differently depending upon their muscle fiber set up.

A genetic-based algorithm for personalized resistance training.
Jones, et al.
Biol Sport. 2016 Jun; 33(2): 117–126.

Avoiding Impingement When Doing Chins or Pull-ups

Shoulder impingement syndrome (SIS) is often diagnosed when pain is located to the shoulder (which is usually worse when the arm is positioned overhead), shoulder weakness, and a loss of shoulder range of motion (ROM). Sometimes, individuals also complain of popping sensations during some shoulder movements. SIS is also called subacromial impingement syndrome, or swimmer's shoulder, or thrower's shoulder. The underlying cause of SIS is believed to be compression of the rotator cuff tendons inside the subacromial space, which is the area under the acromion of the scapula.

Common exercise guidance for the treatment of SIS includes strengthening of the middle trapezius, lower trapezius, serratus anterior and rotator cuff and stretches for the upper trapezius and pectoralis minor, levator scapulae, latissimus dorsi and rhomboids. However, the exact exercise program that is optimal for SIS rehabilitation remains unclear.
The researchers in this study wanted to compare the shoulder and scapular movements of three different pull-up techniques to find any potential injury implications.

The design

They recruited 11 subjects, aged 26.8 ± 2.4 years, who regularly performed pull-ups. All subjects performed 5 sets of 5 repetitions of pull-ups using 3 different techniques: palms pronated, facing anteriorly (away from the subject) using a shoulder-width grip (ANT) as in a regular pull-up; palms supinated, facing posteriorly (towards the subject) using a shoulder-width grip (POST) as in a regular chin-up; and palms pronated, facing anteriorly with a wide-grip (WIDE) as in wide-grip pull-ups.
Shoulder movement was recorded with a 9-camera motion analysis system. Scapula motion was measured using a skin-fixed scapula tracking device.

The findings

There were differences in both shoulder and scapular movements between the three techniques, and these differences altered across the range of motion of the exercise. In particular, there was a much larger range of glenohumeral internal-external range of motion observed in POST/Chins compared to WIDE and ANT, which included starting in a position of high external rotation with the arm elevated.
High degrees of glenohumeral external rotation with the arm elevated have been associated with an increased risk of SIS in athletes. In addition, during WIDE there was much less scapular protraction-retraction range of motion compared to in either POST or ANT, which has been associated with reduced subacromial space, and thereby an increased risk of SIS.

The conclusion

The researchers concluded that supinated pull ups (chins) and wide grip pronated pull-ups display certain features that are associated with greater risk of SIS compared to standard-width grip pronated pull ups.

My thoughts

As Athletic Fitness, where you compete in doing as many wide-grip pull-ups as possible, have become increasingly popular in northern Europe, athletes should probably take precautions by doing exercises that combat the development of SIS. Many of these athletes do wide-grip pull-ups and variations several times a week. Many beginners who look up to these athletes also copy this into their own “back training routines”. One should be especially careful if you perform both the wide grip pull-up (or lat pull-down), a lot of bench pressing and overhead pressing.
If you believe that you are in the risk zone for SIS, make sure to strengthen the middle trapezius, lower trapezius, serratus anterior and the rotator cuff muscles, and do stretches for the upper trapezius and pectoralis minor, levator scapulae, latissimus dorsi and rhomboids.

Scapula kinematics of pull-up techniques: Avoiding impingement risk with training changes.
Prinold, Bull.
J Sci Med Sport. 2016 Aug;19(8):629-35. doi: 10.1016/j.jsams.2015.08.002.

Can Glycine Restore the Anabolic Response to Leucine?

Muscle hypertrophy occurs in response to resistance training and consumption of protein (with more than 2 to 3 grams l-leucine. It is thought that this process of muscle growth occurs by way of an alteration in the balance between muscle protein synthesis and muscle protein breakdown over a sustained period of time. Understanding this process and anything that can interfere is very important not only for those seeking a muscular physique, but also for those trying to come up with good potential treatments for muscle wasting diseases.

In this study the researchers wanted to assess whether the non-essential amino acid glycine can restore the anabolic response to leucine in inflammatory conditions, as measured by changes in muscle protein synthesis (MPS) and in anabolic signaling in rodents. Glycine has previously been shown to have anti-inflammatory, CNS calming, and anti-oxidant properties and has also been found to preserve muscle mass in calorie-restricted rodents.

The design

The team used 20-week-old male C57BL/6 mice, with an average bodyweight of 37 ± 1g. The rodents were randomly allocated into 3 groups: a control group (CON) who were injected with saline solution (13 mice), an intervention group (LPS-LAL) who were each injected with the inflammatory agent lipopolysaccharide but pre-treated with L-alanine (15 mice), and an intervention group (LPS-GLY) who were injected with lipopolysaccharide but pre-treated with the non-essential amino acid glycine (15 mice).
In the two intervention groups, inflammation was induced by intraperitoneal injections of 1 mg/kg of LPS. Injections of LPS in this way represents a simple model of acute inflammation.
The groups then all received injections of 0.5g/kg leucine dissolved in saline via intraperitoneal injection 3 hours after the LPS injection.

The findings

Effects of LPS on MPS and anabolic signaling: MPS tended to be lower after LPS injection in both LPS-LAL and LPS-GLY compared to in CON, by 20 to 25%, but this did not reach statistical significance. These reductions were associated with decreases in the phosphorylation of total Akt and 4E-BP1/4E-BP1 but not mTOR or S6.

Effects of leucine: in CON, leucine increased MPS (by 35 ± 12%), mTOR (by 30 ± 6%) and S6 (by 186 ± 43%). In LPS-GLY, leucine similarly increased MPS by 51 ± 9%, and also increased the phosphorylation of mTOR, S6 and 4EBP1. In contrast, in LPS-LAL, leucine did not stimulate MPS.

The conclusion

The researchers concluded that the non-essential amino acid glycine prevented an inflammatory agent from inhibiting the anabolic effects of leucine in male C57BL/6 mice. This indicates that it may prove to be a useful supplement for reducing muscle wasting in periods of disuse atrophy, cachexia or sarcopenia.

My thoughts

We know that elderly people need more protein since they have a higher resistance to the anabolic properties of leucine. Previous studies have shown that while 20 to 30 grams of whey protein maximizes protein synthesis in young men, older men might need more than 40 grams to see a similar effect. This is probably due to inflammation and a less effective mitochondria and hormone status. Although this study was performed on rodents, it bears promise for future human study models. Adding a few grams of glycine to a serving of protein containing at least 3 grams of leucine might prove beneficial in elderly people suffering from muscle wasting, or in people with chronic inflammation.

Glycine restores the anabolic response to leucine in a mouse model of acute inflammation.
Daniel J. Ham, Marissa K. Caldow, Victoria Chhen, Annabel Chee, Xuemin Wang, Chris G Proud, Gordon S. Lynch, Rene Koopman.
American Journal of Physiology - Endocrinology and Metabolism. 19 April 2016. DOI: 10.1152/ajpendo.00468.2015

Effect of Diet-Induced Only Weight Loss on Muscle Strength

For the initiated, weight loss, or more appropriate, fat loss, is a combination of altering the amount of energy consumed and energy expended through everyday life and possibly exercise. Other important factors include the hormonal environment and hormonal resistance, body inflammation, the efficiency of the mitochondria (our cell’s power house), our gut microbiome/flora, nutrient deficiencies, and much more. While I, as a coach, consider all these factors and more, most people unfortunately only focus on energy intake and expenditure.

In this meta-analysis, the team of researchers went out to perform a meta-analysis to identify the effects on muscle strength from diet-induced weight loss in overweight or obese adults.

The design

They included studies where mostly healthy adults ≥18 years old were included and who had a body mass index (BMI) of ≥25 kg/m2, and used a low calorie diet intervention for producing weight loss, and where muscle strength was measured both at baseline and post-intervention (using either 1RM strength, isokinetic dynamometry, isometric dynamometry, or handgrip strength testing).
The researchers identified 27 studies, including 33 interventions of 8 to 24 weeks. Of the 33 interventions, 12 tested 1RM, 11 employed isokinetic dynamometry, 19 used isometric dynamometry, and 11 implemented handgrip strength. Meta-analyses were only carried out in groups of studies using the same strength test for the same muscle group.

The findings

Effects of low calorie diet on knee extension strength: a meta-analysis of 7 interventions that tested the effects of diet-induced weight loss on isokinetic knee extension torque found a significant decrease of 9Nm (7.5% from baseline), where bodyweight was reduced by an average of 9.2kg, in 108 subjects. There was no significant heterogeneity between studies.

Effects of low calorie diet on handgrip strength: a meta-analysis of 10 interventions that tested the effects of diet-induced weight loss on handgrip force found a non-significant decrease of 1.7kg (3.6% from baseline), where bodyweight was reduced by 8.8kg, in 231 subjects. Heterogeneity was very high (I2 = 84%) and this may have been a function of the type of diet, as there was a significant decrease in handgrip force in 7 of the 10 interventions that employed a moderate energy restriction (2.4kg reduction, 4.6%) but there was no reduction in 3 of the 10 interventions that used a large energy restriction (0.4kg reduction).

The conclusion

The researchers concluded that diet-only induced weight loss can lead to reductions in muscle strength, particularly in the leg muscles, which in turn supports the use of resistance training during periods of dieting, in order to help maintain muscle mass and strength.

My thoughts

No surprises here. Resistance training is your best tool and friend during weight/fat loss.

Effect of diet-induced weight loss on muscle strength in adults with overweight or obesity – a systematic review and meta-analysis of clinical trials.
Zibellini, R. V. Seimon, C. M. Y. Lee, A. A. Gibson, M. S. H. Hsu, A. Sainsbury.
Obesity Review, Etiology and Pathophysiology. 29 April 2016. DOI: 10.1111/obr.12422.

This was an excerpt from Relevant Research in the Field of Strength Training and Sports #17 and 18. For more reviewed studies (6 to 7 each month) and 4 to 5 additional articles every month, please subscribe by clicking the button below. By becoming a subscriber, you'll also get instant access to the archives, featuring more than 280 articles and +20 training programs.

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