Which Exercise Has Your Back?
Comparing the Back Squat with the Weighted Sled Push
We have all been under the bar, fighting to keep our knees out; our chests up until we can stand and re-rack that weight of that final grueling set. What am I talking about – the back squat – nature’s cure to owning a strong, healthy back.
Enter the weighted sled. This thing can be pushed or pulled and leave you wishing you were back on the squat rack for reps – or should it?
Researchers out of Memorial University of Newfoundland in St. John’s Newfoundland, Canada sled examined this resistance exercise by measuring lower-limb and trunk muscle activation during exercise using both the weighted sled push and the back squat.
Before we dive into the meat of their results, let’s consider the practical implications here. Depending on which muscles are recruited, we may see a shift in workout programs, particularly at the collegiate and divisional levels. The back squat is a proven strength and power builder, after all. Athlete’s may be spending less time in the squat rack and more time on the turf or indoor arena pushing and pulling to the finish line. After all, the research is strong among utilization of the sled pull for developing athletic speed. So, what about pushing it?
Here, the authors highlight the fact that the squat is a ground-based resistance exercise that utilizes similar muscles for running, sprinting and jumping. They champion the use of the sled (in studies that showed a pulling movement with the athlete harnessed in and facing away from the sled) because it “athletes move on a horizontal plane [change of direction] with their body at various inclinations depending on the sport or action”. So, it can be postulated that pulling a sled would not only give you the advantage of mimicking a sprinting stance (under the tension of the sled), but that it may also mimic more closely the sport of the athlete as well as improve their speed.
Further, the researchers point out that during sprinting-based pulling exercises using the weighted sled that different weights would alter the torso angle of the athlete, either causing excessive lean that may not mimic the sprinting, thus negatively altering the force-length relationship of the quad-hamstring complex as well as increase the relative angle of the hip flexors. It has been noted though that sled pulls among sprinters using 10% of their body weight did not alter the relative gait / form of the resisted sprint, which would have positive implications during speed training.
The researchers took 10 healthy, resistance-trained men who must have a minimum of 2 years of resistance training and squat experience. All participants completed the study.
The model was a randomized cross-over design that consisted of 2 preparation sessions and 2 testing sessions separated by 2 – 5 days. Testing was done at similar times of the day to negate the effects of diurnal variation. The researchers took anthropometric measurements of the subjects. and began with identical warm ups (5 minutes on a cycle ergometer at 60rpm with a resistance of 1 kp).
Here, the experimenters determined each athlete’s 20-step maximum push, as well as 10 repetition maximum with a bilateral leg squat. Note, that these values were determined on separate days. The 20 step and 10 rep values were chosen to closely resemble the relative limb movement involved in “10 steps per limb”.
For muscle activation, the researchers chose: lower quadriceps, gastrocnemius, lower abdominals (transverse abdominis and internal obliques) and lower erector spinae via electromyography (EMG) during the concentric contraction phase of muscle movement.
During testing, for both the sled push and back squat, individuals were given half the total volume (i.e. 10 steps for sled push, 5 back squats) at 25, 50, 75 and 100% of their maximum values (with 3 minute rests in between). Individuals were measured according to the American College of Sports Medicine in terms of squat (to, but not below 90 degrees) and sled pushing technique; and for their relative 1RM for this study.
The researchers found that with the weighted sled push, that the gastrocnemius had a higher EMG response. The back squat had a higher lower erector spinae EMG response. There was no measurable difference among the rectus femoris, biceps femoris, transverse abdominis and internal obliques.
Okay, so it appears that each of these activities have their respective strengths. But how do we apply this to real life, and real-world training programs? Well, for one, the researchers discovered that with the exception of one test subject, the athletes had a two-fold increase in the weight they could push, versus the weight they could squat (arguments can be made about the surface and relative coefficient of friction, however).
Another thing to consider is injury risk. If we know an athlete is recovering from either a lower back injury, or a gastroch injury; one or the other training modality can be implemented (through adequate supervision) so as to preserve athletic conditioning while minimizing injury risk.
To conclude, it would be interesting to see a study that expands upon this one wherein load variation, velocity as well as prolonged training (more sets, reps; longer sled pushing distances) are examined.
Regardless, it should be exciting for those who have read this article up to this point to recognize that both of these exercises have incredible potential during workout programming; both from a team as well as individual effort. Each of these activities are designed to build strength, power and speed – exactly what you want in an athlete.
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