Relevant Research in the Field of Strength Training and Sports #6

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Relevant Research in the Field of Strength Training and Sports #6 2016-10-16T16:41:16+00:00

Relevant Research

in the Field of Strength Training and Sports #6

Written by: Joachim Bartoll
Classic Muscle Newsletter, May 2015 (issue #9)

 

This is an excerpt featuring only four studies. Each issue normally features 6 to 8 studies.

 

Relevant Research in the Field of Strength Training and Sports: 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.

 

Will different angles in the bench press increase activation in the upper or lower chest?

The research comparing the different bench press variations is limited. It has been reported that the decline bench press can be used for specifically targeting the lower part of the pectoralis major and that it can be further targeted by selecting a narrow rather than a wide grip. Furthermore, using a wide grip during bench press variations has been found to reduce the involvement of the triceps brachii, while using a narrow grip can increase their involvement.

The researchers in this study wanted to compare the muscle activity of the upper and lower pectoralis major, anterior deltoid and triceps brachii muscles during the barbell bench press performed at 0, +30, +45 and -15 degrees (of bench angle.) EMG was normalized to the levels observed during maximum voluntary isometric contractions (MVICs).

The researchers picked 14 healthy and trained males (21.4 ± 0.4 years old) for the study.

The design

The participants undertook 2 training sessions; in the first session, they were asked to complete 1 repetition maximum (RM) in the horizontal bench press. On the second session, fitted with electrodes to assess muscular activation, the subjects performed 1 set of 6 repetitions for each variation of the bench press with a load equivalent of their 65% of 1RM.
Surface electromyography (sEMG) was utilized to examine the muscular activation of the upper and lower pectoralis, the anterior deltoid and triceps brachii during the eccentric and concentric phases. In addition, each phase was subdivided into 25% contraction durations, resulting in four separate time points for comparison between bench conditions.

The findings

The sEMG of upper pectoralis displayed no difference during any of the bench press angles when examining the complete concentric contraction, however differences during 25-50% contraction duration were found at all angle variations. For the lower pectoralis, the anterior deltoid and the triceps brachii, variations was observed during the full concentric and eccentric movement in all angles.

 

-15° decline

horizontal

30°  incline

45°  incline

Upper pectoralis

96.1 ± 5.5%*

98.2 ± 5.4%*

122.5 ± 10.1%*

124 ± 9.1%*

Lower pectoralis

100.4 ± 5.7%

100.1 ± 5.2%

86.6 ± 4.8%

71.9 ± 4.5%

Anterior deltoids

58.3 ± 30.7%

76.0 ± 37.0%

90.9 ± 44.3%

97.5 ± 39.3%

Triceps brachii

102.2 ± 26.5%

106.0 ± 28.7%

114.3 ± 26.3%

117.8 ± 28.5%

*) only registered during 25-50% contraction duration

The conclusion

The researchers concluded that the results support the use of a horizontal bench to achieve muscular activation of both the upper and lower heads of the pectoralis.

My thoughts

This study confirms prior results from various sEMG based studies. As you increase the angle of the bench, muscle activation “moves” upward and outward, i.e. the activation in the anterior deltoids and triceps brachii increases and the activation of the lower pectoralis decreases. To some extent you can also say that the activation of the upper pectoralis increases as well.
Since this study was an acute investigation, it’s still unclear if these differences in muscle activation would affect gains in muscle strength and size over a longer period of time.

Influence of bench angle on upper extremity muscular activation during bench press exercise.
Lauver JD, Cayot TE, Scheuermann BW.
Eur J Sport Sci. 2015 Mar 23:1-8.
http://www.ncbi.nlm.nih.gov/pubmed/25799093

Is going to muscular failure necessary for strength and hypertrophy?

It’s once again time to beat on this old dead horse. This time the researchers set out to compare the increases in muscular strength (as measured by 1RM elbow flexion and maximum voluntary isometric contraction (MVIC) elbow flexion torque), muscle size (as measured by magnetic resonance imaging (MRI) of the elbow flexors), and neural activation (as measured by electromyography

[EMG]) between three resistance training programs.

The researchers picked 28 untrained males who first undertook a 4-week period of “standardized” resistance training to muscular failure. After this introduction they were split into three groups.

The design

All three groups performed a 12-week resistance training program comprising of 4 sets with 85% of 1RM for the elbow flexors, training three times a week.
The failure group performed all sets to muscular failure (unable to lift the weight), which typically meant about 6 repetitions per set. They trained using a 2-second concentric and a 2-second eccentric muscle action.
The fast-concentric-not-to-failure group trained without going to muscular failure and performed 4 repetitions per set. They trained using a maximal concentric and a 2-second eccentric muscle action. The last group, the fast-not-to-failure group trained without going to muscular failure and performed 4 repetitions per set. They trained using both a maximal concentric and a maximal eccentric muscle action.
Both not-to-failure groups did however perform 1 set per week to failure in order to ascertain the loading for the subsequent week.

The findings

The researchers reported that all three groups increased their strength in the elbow flexion 1RM (median increase of 31%) and MVIC elbow flexion torque (median increase of 13%). There were however no significant differences between the groups.
They also reported that all three groups increased their muscle size in the elbow flexors (median increase of 11%). However, there were no significant differences between the groups.
And lastly, they also reported a significant increase in the agonist EMG activity during 1RM performance (median increase of 22%). And yet again, there were again no significant differences between groups.

The conclusion

The researchers concluded that training to muscular failure is not necessary to elicit significant neural and structural changes to skeletal muscle.

My thoughts

Since the non-failure groups stopped about 2 reps short of failure, the failure group performed a greater volume of training (about 33% more repetitions and weight lifted every week). That is a significant difference! Still the non-failure and lower volume groups produced the same results.
Also, the non-failure groups did one of the sets to failure, which probably also interfered with the results.
Also, the fast-concentric-not-to-failure group is not really relevant since the participants were untrained, which means that their central nervous system was not conditioned to really recruit more muscle fibers by using a higher tempo. That skill of accelerating and producing maximum force takes time to develop.
Finally, using the elbow flexor (biceps) in a study setting like this with 4 and 6 reps is somewhat dumbfounded since the biceps main function is to pull and hold (as in carry). Biceps respond better to longer time-under-tension and somewhat more volume.

Is repetition failure critical for the development of muscle hypertrophy and strength?
Sampson JA, Groeller H.
Scand J Med Sci Sports. 2015 Mar 24. doi: 10.1111/sms.12445.
http://www.ncbi.nlm.nih.gov/pubmed/25809472

The effect of knee wraps on knee and hip joint angle movements during the squat

From previous EMG research, we know that different stance widths during squats are unlikely to develop different parts of the quadriceps. However, using a wider stance does appear to increase the activity of the gluteus maximus muscle during squats.
In this study, the researchers wanted to assess the acute effects of knee wraps on knee- and hip joint angle movements and on muscle activity of the vastus lateralis and gluteus maximus during the back squat at two different loads.

The researchers recruited 14 resistance-trained males (24 ± 4 years), with 3 ± 1 years of training experience with the back squat.

The design

There were 4 different conditions: knee wraps and no knee wraps as well as either a high load (90% of 1RM) or a low load (60% of 1RM).
The subject performed 1 set of 3 reps of the back squat to below parallel for all four conditions.

The findings

Muscle activity in both the vastus lateralis and the gluteus maximus muscles increased in all conditions when the load was increased from 60% of 1RM to 90% of 1RM.

When using knee wraps at 60% of 1RM, muscle activity was increased in both muscle groups compared to not using knee wraps.

When using knee wraps at 90% of 1RM, muscle activity decreased in the vastus lateralis, while it was unchanged in the gluteus maximus.

When the load was increased from 60% of 1RM to 90% of 1RM it led to a significantly reduced peak hip flexion angle in the no knee wraps condition and reduced peak knee flexion angle in the knee wraps condition. These reductions in joint angles were accompanied by reduced vertical bar distance traveled.

The conclusion

The researchers concluded that an increase in load with and without knee wraps during the back squat lead to increased muscle activity in the vastus lateralis and gluteus maximus. They also concluded that the use of knee wraps at high loads led to reduced muscle activation of the vastus lateralis but not in the gluteus maximus. They suggested that this reduction in muscle activity might be caused by the storage of elastic energy in the knee wraps, which makes the movement easier to perform.

My thoughts

Previous studies has shown an increase in peak force of about 21 to 22% with use of either high knee wraps or soft knee wraps during a maximum voluntary isometric contraction in the squat.
This study was limited in the way that the researchers only let the subjects perform one set. It’s also unclear to what degree the muscle activity shifted at 90% of 1RM with knee wraps. In my opinion, they should also have measured the activity of the hamstring muscle, which is more involved than the vastus lateralis in a proper deep back squat.
With that said, using knee wraps during your max week could be a good way to further increase the load and possible gains before entering a deload week.

Kinematic and sEMG analysis of the back squat at different intensities with and without knee wraps.
Gomes WA, Brown LE, Soares EG, Silva JJ, Silva FH, Serpa ÉP, Corrêa DA, Vilela Junior GB, Lopes CR, Marchetti PH.
J Strength Cond Res. 2015 Mar 10.
http://www.ncbi.nlm.nih.gov/pubmed/25763519

Can cooling muscles after training hamper muscle growth and adaptation?

The researchers’ objective with this study was to assess the effects of regular post-exercise cold application on gains in muscular size and strength as a result of a long-term resistance training program.
The research team picked 14 recreationally active male subjects (20.2 ± 0.9 years old), and then randomly allocated them into either a cold application group or a control group.

The design

All subjects participated in a resistance training program 3 times a week for 6 weeks. The training consisted of 5 sets of 8 repetitions on a wrist-flexion machine at workload of 70 to 80% of their 1RM.
In the cooled group, the 7 subjects immersed their forearms in a constant temperature bath unit with cold water (10 ± 1 °C) for 20 minutes after the wrist-flexion exercise, while the other 7 participants did nothing and served as control subjects (non-cooled group).
Measurements were taken before and after the 6 weeks of training. The researchers measured wrist-flexor thickness, brachial-artery diameter, maximal muscle strength, and local muscle endurance (in the upper extremities).

The findings

The researchers found that the force generated at a maximal isometric wristflexion only increased significantly in the control non-cooled group and not in the cooled group.
They also found that the thickness of the wrist-flexors increased in both groups, but the control non-cooled group experienced a more pronounced increase in thickness than the non-cooled group.
Finally they also discovered that while muscle endurance increased in both groups, the increase in the cooled group tended to be lower compared to the control non-cooled group.

The conclusion

The researchers concluded that the regular application of cooling exercised muscles post-exercise appears to attenuate muscular and vascular adaptations to resistance training.

My thoughts

Since cold therapy decreases inflammation, which is the response of any form of stress (in this case resistance training), these discoveries are hardly surprising. While cold therapy might reduce the need and time for recovery, it might also reduce adaptations such as increases in strength and hypertrophy. One might however suggest that athletes in some sports might benefit more from an increased rate of recovery than from a greater increase in strength, muscle endurance and muscle mass – especially if the increased rate of recovery let them train more frequently, that the difference is actually negligible and the improvements to neural adaptations and technique will be greater.
One should also consider that the study was limited to only test a very small muscle group such as the wrist-flexor. The subjects in the study was also untrained. Different results might be observed in other muscle groups and in other populations such as well-trained athletes.

Does Regular Post-exercise Cold Application Attenuate Trained Muscle Adaptation?
Yamane M, Ohnishi N, Matsumoto T.
Int J Sports Med. 2015 Mar 11.
http://www.ncbi.nlm.nih.gov/pubmed/25760154

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