As a personal trainer or strength coach, exercise selection is arguably the key component of a successful training plan. Recently I’ve read several articles arguing the superiority of one single lower body exercise as a dominant movement for strength, power, hypertrophy development etc. In reality limiting yourself to a single exercise is a poor notion. It’s critical to understand there are numerous benefits and disadvantages of the back squat and leg press and understanding the strengths of the back squat and leg press separately will help you as exercise professionals select the correct modality for the client’s specific goals:
1) Hormonal response to back squat vs. leg press (Aaron et al., 2014)
Resistance training is often used as a modality to stimulate acute increases in circulating hormones, including testosterone, growth hormone and cortisol. Although it’s safe to say that most exercises influence these hormones. It is also logical to suggest that different exercises have unique effects on circulating hormones.
Kang et al., (1996) demonstrated this very well when examining growth hormone. They concluded that, when comparing rep ranges, high levels of lactic acid and growth hormone occur at a 10RM on the leg press, whereas the back squat elicited the highest levels of growth hormone after completing a 25RM set.
More recently Aaron et al., 2014 looked at the hormonal response in more detail. They compared 6 sets of 10 reps at 80% 1RM with 2 minute rest periods on either the leg press or the back squat, looking specifically at testosterone, growth hormone and cortisol. The results demonstrated that both exercises elevated testosterone levels, however the squat was significantly superior to the leg press. The researchers attributed this to the fact that the back squat activates a greater amount of muscle mass, as even the upper body is required to support the weight. The same was observed for growth hormone and cortisol. In summary the researchers suggest that when the personal trainer or strength coach is looking to induce a greater hormonal response, the back squat is superior to the leg press.
2) Muscle activation patterns to back squat vs. leg press (Barrentine et al., 2001)
Another important factor to consider is the muscle activation pattern of both modalities. Barrentine et al (2001) compared the back squat to:
- A high foot placement leg press (LPH)
- A low foot placement leg press (LPL)
In addition to the different leg press variations, the researchers also examined a narrow foot stance (NS) and wide stance (WS) in both the LPH and LPL. The researchers concluded that:
- The back squat elicited greater quadriceps and hamstring muscle activation than any variation of leg press
- The WS LPH produced greater hamstring activity than the NS LPH
- No Anterior Cruciate Ligament force was observed in any exercise variation
The researchers concluded that when the goal is hypertrophy or strength development, the back squat looks to be optimal. Interestingly they also established that, due to the lack of ACL forces, any variation of the listed exercises is suitable during ACL rehabilitation.
3) Transfer of training to functional strength
Before we begin discussing the transfer of the exercise to functional strength, we define functional strength as the ability to carry over the training effect to human movement, so running, jumping, pulling, throwing etc. The back squat has been shown in numerous studies to improve sprint performance, vertical jump and even endurance cycling. The question then remains can the leg press do the same? Karlsen et al., (2009) demonstrated that walking efficiency (determined by oxygen consumption for the same workload) could be improved by over 30% following 8 weeks of leg press training. Corret et al., (2012) demonstrated that 12 weeks of leg press training in a periodised program could increase jump height by over 8cm.
While it remains apparent that the leg press can improve functional strength the question remains, is it as effective as the back squat… and unfortunately it probably isn’t. However there are populations, such as the elderly or with contraindications that prevent the back squat been utilised, where we can use the leg press as an excellent tool to improve functional strength and makers of athleticism and health.
In summary the back squat results in a greater hormonal response and has superior muscle activation patterns. Both the back squat and leg press have been shown as suitable approaches to improve functional strength. Although the back squat maybe superior, the leg press is still an highly effective approach.