September Strength & Conditioning Research Questions

Hi fitness folks! Do you know the answer to the September 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 block periodization best for strength—power training in track and field?
  2. What factors are important when using block periodization in track and field?
  3. What field tests are associated with track and field ability?
  4. Can eccentric training enhance strength and flexibility in national-level track sprinters?
  5. Does sled towing improve sprint running speed in youths of all ages?
  6. Do anabolic signaling responses differ between high-volume and high-load workouts?
  7. Is high-volume resistance training better for increasing strength and size?
  8. Do cluster sets allow greater volume loads to be performed?
  9. Does variable resistance training increase strength and size more than constant load training?
  10. Can manual resistance increase strength as much as conventional resistance training?
  11. Does plyometric training improve soccer-specific performance in youth soccer athletes?
  12. Does plyometric training change muscle fiber type?
  13. Do resistance training and plyometrics improve sprint running ability in youth soccer athletes?
  14. What determines pull up performance in trained athletes?
  15. Does post-exercise cold water immersion impair muscular adaptations to resistance training?

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Biomechanics & Motor control

  1. Do both pushing more and braking less improve accelerating sprint performance?
  2. Is the hip thrust a better exercise for the gluteus maximus than the back squat?
  3. How does squat variation affect lower body muscle activity?
  4. Does resistance training change the spatial distribution of muscle activity?
  5. How does muscle activity change with relative load during the knee extension?
  6. How does muscle activity change with relative load during the back squat?
  7. Which manual strength testing positions are best for the 3 portions of the gluteus medius?
  8. Are measures of lower body muscle size and 1RM power clean related?
  9. Are maximum isometric strength and vertical jump height related?
  10. How does spine movement differ when the overhead press is performed in front of the head or behind the head?
  11. Is the repeated bout effect exercise-specific?
  12. Does extracellular matrix remodeling contribute to the repeated bout effect?
  13. Can changes in motor neuron excitability explain the post-activation potentiation effect?

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Anatomy, Physiology & Nutrition

  1. Do long-term measures of muscle protein synthesis correlate with gains in muscle size?
  2. Does muscle hypertrophy caused by myostatin inhibition accelerate degeneration?
  3. Is higher protein intake associated with greater muscle mass?
  4. Can diary protein intake increase reductions in fat mass during resistance training?
  5. Does leucine affect anabolic signaling differently from the other essential amino acids?
  6. Can plant-based protein support muscle growth?
  7. What causes the loss of strength relative to muscle size in the elderly?
  8. Does melatonin work for primary sleep disorders?
  9. How do contraceptives affect hormone responses to training sessions in elite athletes?
  10. What are the metabolic effects of non-nutritive sweeteners?
  11. Do resting metabolic rate and lean mass drive energy intake?
  12. Are reduced inhibitory control and increased trait impulsivity key features of obesity?
  13. Is sedentary time associated with visceral fat deposits?

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Physical Therapy & Rehabilitation

  1. What causes exercise-induced rhabdomyolysis?
  2. Can gluteus maximus inhibition occur in cases of proximal hamstring tendinopathy?
  3. Do both tendon stiffness and muscle activity change in Achilles tendinopathy?
  4. Is hip muscle exercise more effective than knee muscle exercise for patellofemoral pain?
  5. Is there a difference in pelvic floor muscle activity across the phases of the menstrual cycle?
  6. Is pelvic floor muscle contraction associated with and diaphragmatic motion when breathing?
  7. Do individuals with uncontrolled lumbopelvic rotation activate the psoas major to a lesser extent?
  8. Can the “doming of the diaphragm” technique increase flexibility?
  9. Does PNF stretching cause larger changes in stretch tolerance than static stretching?

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Squats Versus Hip Thrusts Part III: Forcetime Data

Quick Summary:

  • Squats involve almost twice as much range of motion (ROM) in terms of barbell displacement than hip thrusts, in addition to more time under tension at identical rep ranges
  • The force output during the eccentric phase during squats is only around 10% lower than it is during the concentric phase, whereas the force output during hip thrusts is almost 3X greater during the concentric phase compared to during the eccentric phase
  • Individuals tend to let gravity lower the bar during hip thrusts, whereas much more muscular output is involved during the lower phase when squatting
  • The hip thrust generates greater concentric force output than the squat, whereas the squat generates greater eccentric and total force output than the hip thrust
  • Due to the greater ROM, TUT, and eccentric force output involved in squatting, the squat produces greater total work, total impulse, and total power outputs than the hip thrust
  • The squat is a large ROM concentric and eccentric exercise, whereas the hip thrust is a short ROM mostly concentric exercise
  • Future research should be undertaken to confirm these findings; to split each variable of interest into concentric and eccentric components; to test different styles of squatting and hip thrusting; to determine how anthropometry effects forcetime data, and to determine how these variables of interest impact neuromuscular adaptations

Hi Fitness Friends! This is part III of a 5-part series on squats versus hip thrusts. The data from this series comes from my doctoral thesis, which should hopefully be posted online for anyone to read next year (assuming I pass my defense in December…wouldn’t it be hilarious if I hyped this up and then failed my defense and PhD?). Parts I and III look at mechanistic data, namely what happens when you perform the two exercises while wearing electrodes or while on top of a force plate. Parts II and IV will look at what actually happens following a 6-week training protocol. Part V will summarize the findings and point out limitations and directions for future research. I posted part I three weeks ago and part II two weeks ago, and I’ll post parts IV andV over week or so.

This study portrays an awesome aspect of learning as a researcher as I ended up being wrong and changing my stance. My PhD supervisor John Cronin wanted me to carry out force plate research on the squat versus the hip thrust as part of my thesis (I didn’t want to at the time we planned it). Several years ago, I wrote an article about how silly I think forcetime data is with regards to optimal exercise selection (see HERE). Since then, my stance has softened, primarily due to the process involved in the present study I’m discussing – one can indeed glean valuable and practical information from performing exercises on a force plate and analyzing the data. However, longitudinal training studies are needed to test and validate any hypotheses that are generated from the mechanistic forcetime data.

Prior to the study, I was talking on the phone to my colleague Andrew Vigotsky. Here’s what I said to him. “Andrew, this study is so stupid. People are stronger in the hip thrust compared to the squat. The hip thrust is also the more explosive lift. Since force equals mass times acceleration (f = ma), the hip thrust will generate greater force. And since force output lays the foundation for work since work equals force times distance (w = fd), impulse since impulse equals force times time (i = ft), and power since power equals force times velocity (p = fv), the hip thrust is going to kick the shit out of the squat in every category. This study is merely a formality to show the obvious.”

Turns out I was quite wrong. Had we just looked at concentric data, I might indeed have been right (well, definitely for force and probably for power, but maybe still not right for work and impulse). However, what I failed to consider ahead of time was the eccentric phase and how this impacted total outputs that combined the concentric and eccentric phases. This isn’t the first time I’ve been wrong as a scientist and it sure won’t be the last time. What’s important is that I update my knowledge-base, inform my followers about the truth, and learn from the experience (which I’m doing). Now let’s talk specifics.

We had ten fairly strong dudes with an average of around 7 years of resistance training experience and a 10RM of around 216 lbs in the squat and 252 lbs in the hip thrust perform the two lifts on a force plate. Luckily, I spoke to badass UK biomechanics researcher Jason Lake prior to collecting my data – he was adamant about having the subjects hover silently on the force plate for a moment before starting their sets and performing their reps. This allows for the system load to be cancelled out when analyzing the data so that only the effects of muscular effort can be examined (we want to know what the muscles do, not what gravity + muscles do in concert with the body + barbell system).

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Here are the results:

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When I got the data, my initial instinct was like, “This is all off, there’s no way this is correct, something screwy occurred with the software.” At this point, I hadn’t looked at barbell displacement, time under tension, or concentric force, so the data didn’t make sense to me. I pondered what I knew about biomechanics and what factors could have impacted the data to come out the way they did. I decided to have my assistant check out barbell displacement, and I was shocked to find out how much greater ROM was used in the squat compared to the hip thrust.

I recall back when I invented my Skorcher, I tested barbell ROM in the hip thrust and it wasn’t much different compared to a parallel back squat or sumo deadlift. But the Skorcher involves more ROM than the traditional hip thrust because the feet are also elevated and the dorsiflexion that occurs throughout the concentric ROM translates into greater vertical bar displacement (not the case in the standard hip thrust off of a bench). In addition, we examined the full squat in this study, not the parallel squat. Hip ROM isn’t drastically different in a squat compared to a hip thrust depending on how the two lifts are performed and depending on the height and anatomy of the lifter, but since there’s not much knee ROM in a hip thrust, the total ROM in a squat is much higher. So this makes sense indeed.

Nevertheless, I went out to my garage and performed a set of barbell hip thrusts with a meter stick lined up with the barbell – turns out the forceplate/motion capture data was legit and my assumptions were off-based. I also had my assistant check out time under tension, and it wasn’t surprising to see that the squat took more time due to slower lowering speeds and more ROM.

Next, I asked my assistant to split up the concentric and eccentric force phases, and this is when I discovered how glaringly different the force outputs are during the lowering phases of the two lifts.

Between the differences in displacement, time under tension, and eccentric force, all of the data make perfect sense. Now, one could astutely point out that lifters can indeed lower the barbell slowly during a hip thrust if instructed to do so. What’s great about this study is that we examined what people naturally do during the two lifts. Future research can examine how the effects of hip thrusts with controlled eccentric phases impact forcetime data, or how higher box heights (this study used a box that was around 16″ high) impact forcetime data, or how anthropometry impacts squat versus hip thrust forcetime data, etc.

You’ll note that we didn’t separate all variables into concentric and eccentric phases. This is because my thesis deadline came to an end and we ran out of time. Had we had more time, I surmise that the hip thrust has greater concentric power outputs than the squat, but I’m not sure about concentric work and impulse. Everybody in S&C loves to talk about eccentrics, but it’s important to note that acceleration sprinting is mostly concentric in nature. This could impact training adaptations.

To wrap things up so far, Part I demonstrated a clear advantage of the hip thrust over the squat in terms of EMG activity. Part III (this article) demonstrated a clear advantage of the squat over the hip thrust in forcetime data (force, work, impulse, power) and displacement. Part II provided some clues as to how the two lifts differ in terms of actual training adaptations. In part IV, we’ll look at the effects of an actual training study in performance. These are vital in S&C as they show what DOES happen, not what SHOULD happen based on humans’ often limited and biased opinions pertaining to acute mechanisms, sensations, and transfer of training theories. In part V, I’ll wrap it all up and summarize my findings.

Strength & Conditioning Research Preview: Muscle Activity Edition

The S&C Research review service comes out on the first day of every month. Here is a preview of the September 2015 edition, which comes out next Tuesday. Each edition covers a wide range of exciting new research but this edition has a special theme of muscle activity.

Unless you have been living in hibernation for these last few weeks, you will doubtless have seen the recent studies investigating the differences in muscle activity between resistance training exercise performed with high and low loads. In this edition, we review these and discuss what they actually mean.

Does knee extension exercise with high or low loads lead to higher muscle activity?

The study: Muscle activation during three sets to failure at 80 vs. 30% of 1RM resistance exercise, by Jenkins, Housh, Bergstrom, Cochrane, Hill, Smith, & Cramer, in European Journal of Applied Physiology (2015)

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What did the researchers do?

The researchers set out to compare the muscle activity (as measured by the surface electromyography [EMG] amplitude and mean power frequency), changes in quadriceps muscle cross-sectional area (CSA) (as measured by ultrasound), and volume load (as measured by repetitions multiplied by weight lifted) during 3 sets of resistance exercise to muscular failure at 80% and 30% of 1RM resistance exercise

What happened?

Regarding EMG activity, the researchers noted that this was greater at 80% of 1RM than at 30% of 1RM across all repetitions and sets. However, they found that EMG mean power frequency decreased more and was lower for the last repetitions during the 30% of 1RM condition than during the 80% of 1RM condition, possibly as a result of greater metabolic byproduct accumulation and/or greater reductions in intramuscular pH. Regarding muscle CSA, the researchers found that acute changes were greater after the 30% of 1RM condition than after the 80% of 1RM condition, most likely because of exercise-induced cell hydration and/or cell swelling.

Regarding volume load, the researchers found that this was greater for 30% of 1RM than for 80% of 1RM during all sets. This was because the number of repetitions was much greater for the 30% of 1RM condition (for set 1: 45.6 ± 14.3 repetitions vs. 8.9 ± 2.7 repetitions). These results indicate that although EMG activity was greater when using the heavy load, volume load and fatigue (as shown by both greater increases in CSA and greater reductions in mean power frequency) were greater when using the lighter load.

To learn why these findings are very exciting for our understanding of long-term muscular adaptations, pick up a copy of the monthly review HERE so you can read Chris Beardsley’s editorial.

Do back squats with high or low loads lead to higher muscle activity?

The study: Electromyographical and Perceptual Responses to Different Resistance Intensities in a Squat Protocol: Does Performing Sets to Failure With Light Loads Recruit More Motor Units? By Looney, Kraemer, Joseph, Comstock, Denegar, Flanagan, Newton, Szivak, DuPont, Hooper, Häkkinen, and Maresh, in Journal of Strength & Conditioning Research (2015)

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What did the researchers do?

The researchers compared the muscle activity of the vastus lateralis and vastus medialis (measured using EMG) across several different conditions in resistance-trained subjects. Firstly, they compared EMG activity during sets of back squats with either maximal or sub-maximal numbers of repetitions with 50% of 1RM. Secondly, they compared EMG activity between light and heavy relative loads (50% of 1RM vs. 90% of 1RM) performed with maximal numbers of repetitions. Thirdly, they compared EMG activity during sets with 50% of 1RM between rested and pre-fatigued conditions (during a drop set). In addition, rating of perceived exertion (RPE) was measured (using the Borg 0–10 category-ratio scale).

What did the researchers find?

The researchers observed that EMG activity in both vastus lateralis and vastus medialis was significantly greater in the 90% of 1RM set to muscular failure compared to the 50% of 1RM set to muscular failure. Also, EMG activity in the 50% of 1RM set to muscular failure was greater than in the 50% of 1RM set of sub-maximal repetitions. However, pre-fatigue using a drop set format did not increase muscle activity above the levels seen during muscular failure.

Also, the researchers found that RPE did not differ with relative load when sets were performed to muscular failure. On the other hand, RPE was lower in the sub-maximal sets than in the maximal sets. These findings add to existing literature by supporting previous findings that have reported greater EMG activity with heavy loads compared to lighter loads, and greater EMG activity when exercising closer to muscular failure than further from muscular failure. In addition, they break new ground by demonstrating that, just like the pre-exhaustion technique, drop sets do not lead to greater muscle activity than standard methods of resistance training. Finally, they make it clear that RPE is not affected by relative load but is affected by the proximity to muscular failure.

To learn why these findings are valuable for an understanding of long-term muscular adaptations, pick up a copy of the monthly review HERE so you can read Chris Beardsley’s editorial.

Get the full review!

The next edition comes out on Tuesday. Don’t forget, the full edition contains far more than just these two reviews. It is packed full of 50 study reviews covering a range of topics relevant to strength and conditioning and physical therapy professionals alike. It only costs $10 per month so sign up by clicking below!

 

10 Steps to the Perfect Hip Thrust

The hip thrust is likely the most rapidly rising exercise in terms of popularity in strength & conditioning. It is performed by physique athletes, strength athletes, and sport athletes alike. Hip thrusts can be performed with bodyweight, barbell, or resistance band loading. The barbell hip thrust lends itself well to heavy loads, which is precisely why it’s mandatory to execute the exercise properly and master bodyweight first. Here are ten steps to the perfect hip thrust.

1. Push Through the Heels

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The Benefit:

Pushing through the heels as opposed to through the balls of your feet shifts muscle activation away from the quadriceps and onto the glutes and hamstrings.

How to:

Make sure your heels do not rise off the ground. You can choose to maintain flat feet or to raise your toes off the ground via ankle dorsiflexion and holding that position throughout the set.

2. Ensure Vertical Shins at the Top of the Movement

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The Benefit:

Having the shins vertical and perpendicular to the ground maximizes glute activation. Setting the feet too close to the buttocks shifts more tension onto the quads, and setting the feet too far away from the buttocks shifts more tension onto the hamstrings.

How to:

Figure out the proper foot distance so that when you’re at the top of the hip thrust, in the lockout position, your shins are vertical and not angled forward or backward.

3. Keep Knees Out

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The Benefit:

Keeping the knees out increases gluteal activation and is healthier for the knee joints.

How to:

Don’t let the knees cave inward throughout the set; keep tension on the glutes so that the femurs track in line with the feet.

4. Achieve Full Hip Extension

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The Benefit:

Full hip extension is where the glutes achieve their highest level of activation. Failing to reach this range of motion will lead to diminished tension on the glutes.

How to:

Make sure you use the glutes to push the hips as high as possible during each repetition of the hip thrust. Don’t skimp on ROM just to perform more reps; if you can’t reach full hip extension then end the set.

5. Slightly Posterior Tilt the Pelvis

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The Benefit:

Posterior pelvic tilt prevents lumbar hyperextension which isn’t ideal for spinal health, in addition to increasing glute activation.

How to:

As your hips extend and start to reach the top of the movement, think of bringing your pubic bone closer to your ribcage via gluteal contraction.

6. Keep Ribs Down

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The Benefit:

Keeping the ribs down prevents spinal hyperextension, which can be injurious to the spine over time.

How to:

Many coaches like the “chest up” cue during squats and deadlifts, but for the hip thrust this cue is the opposite of what you want. During the hip thrust, think “ribs down” so that your ribs stay glued to the pelvis throughout the movement.

7. Maintain Forward Eye Gaze

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The Benefit:

A forward eye gaze encourages posterior pelvic tilt and prevents anterior pelvic tilt and lumbar hyperextension while simultaneously shifting tension onto the glutes and away from the erectors and hamstrings.

How to:

Look straight ahead when at the bottom of the hip thrust. As you rise upward, maintain your forward eye gaze which will cause your neck to flex forward during the movement.

8. Make Fists and Dig Arms Into the Bench

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The Benefit:

Digging the arms into the bench and making fists will increase strength and total body muscular tension through a process known as “irradiation.”

How to:

When you set up, get tight, squirm into proper position, dig your arms into the bench, and squeeze your fists together forcefully.

9. Breathe Big and Brace Core Prior Before Each Lift

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The Benefit:

Bracing increases spinal stability, prevents hyperextension of the spine, and allows for better performance.

How to:

At the bottom of the movement, take a deep breathe and then “lock it down” by tightening the abs, obliques, and diaphragm muscles.

10. Pause at the Top with a Big Glute Squeeze

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The Benefit:

Pausing for a moment at the top of the hip thrust increases time under tension and ensures proper tempo and control throughout the movement.

How to:

At the top of each rep, squeeze the glutes and count to one before descending.

How it Looks in Action

The video below showcases some of these tips and portrays how hip thrusts should look in action, delving into bodyweight and barbell mechanics.