January Strength & Conditioning Research Questions

Hi fitness folks! Do you know the answer to the January S&C research review questions? If not, you ought to subscribe to our research review service. To subscribe, just click on the button below and follow the instructions…

 

Strength & Conditioning, Power and Hypertrophy

  1. Is Olympic weightlifting the best way to improve vertical jump height?
  2. Is the PAP effect on vertical jump height caused by central factors?
  3. Are short rest periods best for increasing muscle size?
  4. Does reducing fatigue by using intra-set rest periods affect strength gains?
  5. How do different repetition ranges affect changes in muscle fiber type?
  6. Is there more than one type of block periodization?
  7. How do aerobic training, resistance training, and concurrent training help obese adolescents?
  8. How many people fail to respond to sprint interval training?
  9. Can hill sprints help semi-professional soccer players improve both fitness and strength?
  10. Does self-reported mental toughness predict scores on objective tests of perseverance?
  11. Is trunk muscle strength associated with athletic performance?

hill sprints

Biomechanics & motor control

  1. Which biomechanical factors increase when jump height improves?
  2. Is the jump squat a better predictor of jump height than the push press?
  3. Can external cues help improve jump height in elite high jumpers?
  4. Can combining augmented feedback and external focus of attention enhance jump height?
  5. What biomechanical factors drive performance for 100m sprint finalists?
  6. How do the mid-acceleration and the maximum velocity phases of sprinting differ?
  7. Does hypertrophy increase muscle moment arms?
  8. Does “the increasing role of the hips” apply to stair climbing speeds?
  9. Is the kettlebell swing a good exercise for the gluteus maximus?
  10. Does one workout with an enhanced-eccentric exercise provide a protective effect over a similar workout, four weeks later?
  11. Does nine days of daily drop jump exercise increase tendon size?

swing

Anatomy, physiology & nutrition

  1. Can muscle growth happen within 4 weeks of barbell training?
  2. Is hypertrophy actually greatest in the earliest phase of resistance training?
  3. Is the thermic effect of food bigger in the morning than in the evening?
  4. Does resting metabolic rate reduce after shorter sleep duration?
  5. Does daily overfeeding from protein supplementation improve body composition?
  6. Does protein supplementation increase lean body mass in female collegiate athletes?
  7. Do higher doses of protein produce bigger anabolic responses than moderate doses?
  8. Can vitamin D supplementation help reduce the effects of damaging exercise?
  9. Is greater eating frequency associated with an increased risk of obesity?
  10. Is greater eating frequency associated with an increased risk of central adiposity?
  11. Are appetite hormones different in obese individuals?
  12. Do high load and high volume workouts have different effects on plasma volume?
  13. Is there an association between changes in testosterone and body fat after resistance training?
  14. Does aerobic exercise help reduce the stress response to psychological stressors?
  15. Can adaptogenic supplements help elite athletes adapt to stress?
  16. Is a lack of vigorous physical activity an independent risk factor for all-cause mortality?

arny

Physical therapy & rehabilitation                        

  1. How do static, dynamic and PNF stretching affect performance?
  2. How do static and dynamic stretching produce changes in ROM?
  3. Can using a strap help increase improvements in ankle-dorsiflexion ROM?
  4. Do temperature and time affect reductions in DOMS produced by cold water immersion?
  5. Can massage change passive plantar flexor stiffness?
  6. Is intrinsic foot muscle volume smaller in runners with plantar fasciitis?
  7. How should hamstring muscle injuries be rehabilitated?
  8. Does the force–velocity profile during sprinting alter before or after hamstring injury?
  9. Can the Copenhagen adduction exercise improve eccentric hip adduction strength?
  10. How should neuromuscular electrical stimulation be used to strengthen the quadriceps?
  11. How does superimposed EMS affect long-term physiological adaptations to resistance training?
  12. How does superimposed EMS affect strength and performance gains after strength training?

Copenhagen Adduction

To subscribe to our research review, click on the button below:

 

January Strength & Conditioning Research Preview: Vertical Jump Edition

Every month, Chris and I write the monthly S&C Research review service. Subscribe, and you will learn about the 50 most important sports science studies published every month, covering strength & conditioning, biomechanics, anatomy & physiology, and sports medicine.

strength and conditioning research

You can subscribe HERE or just try it by buying a back issue HERE.

Here is a preview of the January 2016 edition, which covers a wide range of research but has a special theme of vertical jumping.

2011 NFL Scouting Combine

Is Olympic weightlifting best for improving vertical jumping height?

The study: Olympic weightlifting training improves vertical jump height in sportspeople – a systematic review with meta-analysis, by Hackett, Davies, Soomro, & Halaki, in British Journal of Sports Medicine (2015)

What did the researchers do?

The researchers performed a meta-analysis (by calculating Cohen’s d in a random effects model) in order to assess the ability of Olympic weightlifting and weightlifting derivatives on changes in vertical jump height, and to assess whether this form of training is better than either resistance training or plyometrics.

What happened?

The researchers identified that the mean improvement in vertical jump height as a result of Olympic weightlifting training was 8.7% compared to a 1% increase in the control, for a mean difference of 7.7%, which was significant (Cohen’s d = 0.62) and the heterogeneity was very low. This indicates that Olympic weightlifting training is effective for increasing vertical jump height.

The researchers identified that the mean improvement in vertical jump height as a result of Olympic weightlifting training was 7.5% compared to a 2.4% increase in the resistance training group, for a mean difference of 5.1%. This was significant (Cohen’s d = 0.64) and the heterogeneity was very low. In contrast, the researchers identified that the mean improvement in vertical jump height as a result of Olympic weightlifting was 10.2% compared to a 9.0% increase in the plyometrics group, for a mean difference of 1.2%. This was not significant (Cohen’s d = 0.11) and the heterogeneity was also very low. These findings show that Olympic weightlifting is better than resistance training but similar to plyometrics exercises for increasing vertical jump height.

dimas

What biomechanical factors are associated with increasing vertical jumping height?

The study: Biomechanical factors associated with jump height – a comparison of cross-sectional and pre-to-post-training change findings, by Marshall, Moran & Marshall, in The Journal of Strength & Conditioning Research (2015)

What did the researchers do?

The researchers explored the changes in biomechanical factors (as measured using a 12-camera motion analysis system linked to a force platform) that might be associated with long-term increases in counter-movement jump (CMJ) height (as measured with the same technology). Before and after a jump training program, subjects performed 5 maximal CMJs, with 40 seconds of rest between each one. Jumps were performed to a self-selected depth with hands on hips in self-selected athletic footwear. The training program comprised 4 sets of 8 drop jumps, from a 30cm box, 3 times a week for 8 weeks.

What happened?

The researchers found that CMJ height significantly increased by 2.9cm (6%) as a result of the jump training program. At the whole body level, the strongest correlations between CMJ height and the biomechanical measures taken were for concentric work done (r = 0.62) and peak power (r = 0.60). At the individual joint level, the strongest correlations with improved CMJ height were for hip concentric peak power (r = 0.61), hip concentric work done (r = 0.57), and hip angle at joint reversal (r = -0.56) at the individual joint level. These findings underscore the importance of improving hip extension strength and power for enhancing vertical jumping performance.

jump

Get the full review!

The full edition includes 50 reviews, covering strength and conditioning, athletic performance, hypertrophy, physiology, and physical therapy studies. You need to read the full edition so you can stay up to date with the latest research. Sign up by clicking on the button below!

 

Which variation produces greater glute activation: barbell hip thrusts, American hip thrusts, or band hip thrusts?

Highlights:

  1. The barbell hip thrust trumps the American hip thrust and band hip thrust in mean upper gluteus maximus activation (70% versus 57% and 49%)
  2. The barbell hip thrust trumps the American hip thrust and band hip thrust in peak upper gluteus maximus activation (172% versus 157% and 120%)
  3. The American hip thrust trumps the barbell hip thrust and band hip thrust in mean lower gluteus maximus activation (90% versus 87% and 79%)
  4. The barbell hip thrust trumps the American hip thrust and band hip thrust in peak lower gluteus maximus activation (216% versus 200% and 185%)
  5. The American hip thrust leads to slightly (non-significantly) higher hamstring activity than barbell and band hip thrusts and slightly (non-significantly) lower quadriceps activity than barbell and band hip thrusts
  6. Around 85% of subjects received the highest mean upper glute activation when performing the barbell hip thrust (8% for band hip thrust and 8% for American hip thrust)
  7. Around 77% of subjects received the highest peak upper glute activation when performing the barbell hip thrust (15% for band hip thrust and 8% for American hip thrust)
  8. Around 46% of subjects received the highest mean lower glute activation when performing the barbell hip thrust (15% for band hip thrust and 39% for American hip thrust)
  9. Around 39% of subjects received the highest peak lower glute activation when performing the barbell hip thrust (31% for band hip thrust and 31% for American hip thrust)
  10. The aforementioned variability helps explain how some lifters feel their glutes working to a greater degree in one particular variation compared to another, despite their similar average mean and peak values
  11. Due to the nature of incremental band loading, it was difficult to obtain true 10RMs for the band hip thrust, therefore the band hip thrust probably produces slightly higher EMG values than what was reported in the study
  12. Since muscle activation is similar between the different hip thrust variations, comfort, goals, and logistics should be taken into account when determining the optimal hip thrust variation to employ/prescribe
3

Barbell hip thrust

Similar Articles:

Click HERE to see how the hip thrust compares to the back squat

Click HERE to see how full, front, and parallel squats compare to each other

* Special thanks to Andrew Vigotsky, Brad Schoenfeld, Chris Beardsley, and John Cronin for their stellar contributions to this research

 

Which variation produces greater glute activation: barbell hip thrusts, American hip thrusts, or band hip thrusts?
By Bret Contreras

Just today, my team got THIS study published ahead of print in the Journal of Applied Biomechanics. We looked at mean and peak upper glute max, lower glute max, biceps femoris (hammies), and vastus lateralis (quads) during the barbell hip thrust, American hip thrust, and band hip thrust. In case you’re not aware of the different variations, check out this video below:

Here are the tables from the study:

1

 

2

Here are two graphs that didn’t make the study (reviewers tend to think having tables and charts is redundant).

Mean

Mean EMG Amplitudes (BBHT = barbell hip thrust, AHT = American hip thrust, BHT = band hip thrust, UGM = upper gluteus maximus, LGM = lower gluteus maximus, BF = biceps femoris, VL = vastus lateralis)

Peak

Peak EMG Amplitudes(BBHT = barbell hip thrust, AHT = American hip thrust, BHT = band hip thrust, UGM = upper gluteus maximus, LGM = lower gluteus maximus, BF = biceps femoris, VL = vastus lateralis)

To read the full paper, click HERE (this study is published ahead of print so it’s not formatted yet, hence the ugly appearance).

Can motor unit recruitment be inferred from EMG amplitude?

Below is a technical guest blogpost from Andrew Vigotsky. Andrew and colleagues recently wrote a letter to the editor to JSCR contending a claim that researchers made pertaining to a recently published EMG study. The study was in fact very well-conducted and the authors should be commended for their work, but we wanted to raise a small but important point.

In short, greater EMG amplitudes may indeed occur due to greater motor unit recruitment, but researchers who just measure EMG amplitude cannot make this claim, since more factors are at play. Examining actual motor unit recruitment is elaborate and requires specialized techniques. This blogpost does not imply that EMG is useless (as per our previous article), but it does imply that one must be cautious when interpreting EMG findings, especially in dynamic, fatiguing conditions.

Moreover, although exercises with greater EMG amplitudes may indeed provide a more potent stimulus for hypertrophy, just as in the case of motor unit recruitment, claiming that EMG amplitude implies greater hypertrophy would require a separate study examining actual hypertrophy following longitudinal bouts of training. 

Can motor unit recruitment be inferred from EMG amplitude?
By Andrew Vigotsky

In August, a paper by Looney et al. (1) was published ahead-of-print in the Journal of Strength and Conditioning Research. This paper certainly made the rounds on social media, and justifiably so with the claims it made: heavy loads taken to momentary muscular failure recruit a greater number of motor units than light loads taken to momentary muscular failure. This conclusion followed the fact that greater EMG amplitude was observed in the heavy-load condition. The question is, can such a conclusion be drawn from the data presented in this study?

In order to address this, it is immensely important that the constituents of, or components that make up, an EMG signal be understood. These components are:

Neural

  • Motor unit recruitment – the number of motor units that are recruited at any given point in time
  • Motor unit firing rate (rate coding) – the rate at which neural signals are sent the muscle
  • Motor unit synchronization – the timing of how motor units are recruited relative to one another (i.e., how closely, temporally, the firing of each motor unit is to one another)

Peripheral

  • Muscle fiber propagation velocity – the speed at which electrical potential travels over a muscle fiber
  • Intracellular action potentials – potential difference (voltage) created from the movement of ions within a muscle fiber

Glute-EMG1

The authors of the paper in question, Looney and colleagues, purport that motor unit firing rate decreases with fatigue (which would cause EMG amplitude to decrease), and consequently, an increase in EMG amplitude is due to motor unit recruitment. However, especially in fatiguing conditions, such as those studied, this claim is demonstrably false. Therefore, upon reading this study, I reached out to a few of my friends and colleagues – including Chris Beardsley, Bret Contreras, James Steele, Dan Ogborn, and Stu Phillips – to write a letter to the editor or manuscript clarification, which just published ahead of print in JSCR (the full-text is available on ResearchGate). Below are the key takeaways from our letter.

  1. Looney and colleagues studied the quadriceps muscles, which have been shown to have between-muscle differences in neural recruitment strategies. For example, the vastus lateralis may depend on motor unit recruitment, while the vastus medialis may depend on rate coding to maintain force output during fatiguing contractions.
  2. A phenomenon called motor unit cycling may be taking place, wherein addition motor units are recruited and subsequently momentarily derecruited in order to reduce fatigue. As such, at any given point in time, less motor units may be recruited (simultaneously), but over the duration of the set, a comparable number of motor units may ultimately be recruited and fatigued.
  3. The peripheral components of EMG make inferring motor unit recruitment from EMG amplitude extraordinarily difficult, especially in fatiguing conditions. More specifically, with greater fatigue, the more one has to account for intracellular action potentials, for which the authors did not account.
  4. Lastly, the authors attempted to draw longitudinal conclusions from acute data; that is, the authors claimed that, due to greater motor unit recruitment, higher loads would produce greater hypertrophy, while a number of studies have shown this not to be true.

While it is certainly possible that the increased EMG amplitude is due to motor unit recruitment, this cannot be said for certain. In order to study this, more advanced methods are needed, which entail breaking down an EMG signal into the motor units from which it is created. This can be done via spike-triggered averaging or initial wavelet analysis followed by principal component classification of major frequency properties and optimization to tune wavelets to these frequencies. For more details and references, I encourage readers to download our piece and give it a read. Additionally, for those looking to learn more about EMG in general, Chris Beardsley has just released a stellar page on it, which I highly recommend.

As with any letter, the authors were given the opportunity to respond, but they did not take advantage of it.

  1. Looney DP, Kraemer WJ, Joseph MF, Comstock BA, Denegar CR, Flanagan SD, Newton RU, Szivak TK, DuPont WH, Hooper DR, Hakkinen K, and Maresh CM. Electromyographical and Perceptual Responses to Different Resistance Intensities in a Squat Protocol: Does Performing Sets to Failure With Light Loads Recruit More Motor Units? J Strength Cond Res, 2015.