Practical training tips from research in January

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January was a great month for us to take stock of the research that has been coming out. We found some amazing studies that have really useful, practical implications. The February edition itself comes out on Friday and covers nearly 50 of the best studies. In the meantime, in this article, Chris Beardsley (@SandCResearch) reviews three ground-breaking studies that we couldn’t resist sharing in advance.

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Is stretching counter-productive for gaining strength?

Many coaches include stretching before weight training to avoid injury and many bodybuilders use stretching between sets in the belief that it helps increase muscular size. However, this study shows that these practices may be counter-productive.

The study: Chronic effect of static stretching on strength performance and basal serum IGF-1 levels, by Bastos, Miranda, Vale, portal, Gomes, Novaes and Winchester, in Journal of Strength and Conditioning Research, 2012

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What did the researchers do?

The researchers recruited 30 recreationally-trained participants and randomly assigned them into one of 3 training groups, as follows: (1) a group that performed static stretching exercises before beginning strength training exercises, called Stretching-Before, (2) a group that performed static stretching for a specific muscle immediately before the strength exercise for that same muscle between strength training sets, called Stretching-During, and (3) a group that only carried out the strength training program without any stretching either before or during, called No-Stretching. The researchers measured IGF-1 levels as well as the 8RM of various exercises (bench press, lat pull-down, leg extension and leg curl) before and after the 10-week training period.

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What happened?

The researchers reported significant statistical differences between the two stretching groups and the No-Stretching group in respect of the increases in 8RM strength of all 4 exercises tested. Additionally, the researchers reported that IGF-1 expression increased only in the Non-Stretching group and did not increase significantly in either of the two stretching groups. The researchers did not identify any differences between the two stretching groups. The chart below shows the increases in strength in three of the four exercises:

Bastos

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What did the researchers conclude?

The researchers concluded that although all three groups improved 8RM strength as a result of the 10-week training program, the two stretching groups displayed significantly lower gains in strength compared to the Non-Stretching group.

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What were the limitations?

This study had two very important limitations. The study was limited in that only one period of time spent stretching was investigated, which was 30-seconds. Other research has found differences in respect of the acute effects on power production depending on how long stretches were held for (15-seconds versus. 45 seconds). Therefore, stretches of shorter duration may not have the same detrimental effect on strength gains. It is not known whether stretching would similarly effect gains in athletic performance, such as what might be achieved through sprint training or jumping training.

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What are the practical implications?

Strength training programs that are either preceded by stretching routines, or which have stretching routines included in-between sets of strength training, will likely lead to inferior gains in strength.

Bodybuilding routines that involve extreme stretching techniques between sets may be counter-productive to the goal of increased strength and hypertrophy.

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Does the exact content of a warm-up make that much difference to performance?

Many coaches and athletes take a relaxed approach to the content of a warm-up before performing it. However, several recent studies have showed that in several sports, the exact content of the warm-up can have significant ramifications for performance. This study shows how it can affect bob-skeleton speed.

The study: Designing a Warm-up Protocol for Elite bob-skeleton Athletes, by Cook, Holdcroft, Drawer and Kilduff, in International Journal of Sports Physiology and Performance, 2012

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What did the researchers do?

The researchers wanted to assess how the content of various different warm-ups affected subsequent performance in the skeleton, compared to a control warm-up, which was the standard warm-up currently used by the athletes. So they recruited 6 (3 male and 3 female) skeleton athletes who were competing for selection into the British Olympic team and had them perform warm-ups as follows:

  1. A standardized version of the athletes’ own warm-up, taking 20 minutes and being completed 35 minutes before testing. It comprised 3 sets of 20m efforts of jogging and skipping with walking back, 3 sets of 20m sub-maximal sprinting, 3 sets of 20m sprint form drills, 2 sets of 20m leg swings, fast feet and high knees, 3 sets of 10m maximal sprints, 30 seconds of mixed calisthenics (press-ups, dead bugs and planks) and 2 minutes of dynamic stretching.
  2. A variation of the control warm-up but with greater volume and greater intensity on account of more sprint drills and sprints and shorter rest intervals.
  3. Same as the second variation but was completed 15 minutes before testing rather than 35 minutes before testing.
  4. Same as the second variation but was split into 2 blocks of 10 minutes, one which was completed 40 minutes before testing and the second which was completed 15 minutes before testing.
  5. Same as the fourth variation but with a warm garment used for passive heat retention, that was worn in between warm-up activities and up until performance testing.

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What happened?

The researchers reported that the third warm-up variation was found to be the fastest, followed by the fifth and then the fourth. The fifth was the most popular with the athletes and produced an improvement of 3.5% overall across the 6 athletes.

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What did the researchers conclude?

The researchers concluded that intensity, duration and body temperature are all useful for creating an improved warm-up. They concluded that the third warm-up variation, which was identical to the second variation but was completed 15 minutes before testing rather than 35 minutes before testing, was the best. However, the fifth warm-up variation produced a similar performance improvement and was more popular amongst the athletes.

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What are the practical implications?

Athletic coaches should be aware that the exact make-up of warm-ups can make very material differences to the performances of elite athletes, particularly in cold environments.

Greater intensity and completing the warm-up closer to the performance event lead to better performances.

Additionally, heat retention in cold environments clearly makes a difference to performance and heat-retention garments can be used to beneficial effect.

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What effect does squat depth have on muscle activation?

At last, we finally have a study that shows how muscle activity changes with squat depth. (If you’re nonplussed by this statement, check out my review of the Caterisano study at Bret’s blog). Unfortunately, it didn’t look at gluteal activity.

The study: The effect of squat depth on multiarticular muscle activation in collegiate cross-country runners, by Gorsuch, Long, Miller, Primeau, Rutledge, Sossong and Durocher, in Journal of Strength and Conditioning Research, 2012

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What did the researchers do?

The researchers wanted to establish the most effective squat depth for both male and female collegiate cross-country runners by measuring the muscle activity recorded by EMG at each squat depth. Specifically, the researchers wanted to compare the activity of the quadriceps and hamstrings in partial squats at two different knee angles (45 and 90 degrees) with a 10RM load.

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What happened?

Squat performance

The researchers reported that the mean 10RM for the 45-degree squat was 78.4 ± 4.6kg) while the mean 10RM for the 90-degree squat was 51.2 ± 3.1 kg. The 10RM for the 90-degree squat was therefore significantly lower than that of the 45-degree squat.

EMG activity differences with depth

The researchers observed that activity of the rectus femoris and erector spinae were both higher during the 90-degree squat than during the 45-degree squat despite the heavier weight being used in the 45-degree squat. However, they found that the activity of the biceps femoris and gastrocnemius were similar in both squat variations. The chart below shows the differences in EMG activity between squat depths:

Gorsuch

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What did the researchers conclude?

The researchers concluded that the deeper squat displayed increased activation of the rectus femoris and lumbar erector spinae when compared to the shallower squat. They also concluded that biceps femoris and gastrocnemius activity were similar in both shallower and deeper squats.

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What are the practical implications?

Deeper squats are probably better for training the quadriceps and lower back muscles than shallow squats.

Since squats are predominantly a quadriceps-dominant exercise, deeper squats probably give a better overall training effect than partial squats for the same percentage of 1RM.

For more information like this, please check out our research review. Click HERE to see a free preview edition!

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