If you’re pumping iron in the gym with the goal of building muscle, you might be wondering how you can amplify muscle growth. Here at The Manual, we keep an eye on the latest research on getting ripped and maximizing our muscle-building potential. There are ways we can fine-tune our training to achieve better results. Recently, researchers focused on how adjusting training impacts regional hypertrophy (building muscle at different points). Let’s look at the research.
The study
In a study published in the Scandinavian Journal of Medicine & Science in Sports, researchers wanted to determine how a nine-week resistance training program affected muscle growth, either with a high load and low reps or with a low load and high reps. The researchers also wanted to understand how muscle growth took place in hamstring heads. The hamstrings are the large leg muscles on the backs of your thighs.
The study methods
The study involved 45 participants who were already physically active but weren’t doing hamstring-specific weight training at the beginning of the study. The participants were split into three groups: High load (HL), Low load and blood flow restriction (LL-BFR), and the control group (CON).
The study methods were as follows:
- The HL and the LL-BFR group completed a 9-week resistance training program that included three weekly sessions involving alternating stiff-leg deadlifts and front squats or seated leg extensions and seated leg curls.
- The HL group completed exercises with a 12-rep max while gradually increasing intensity.
- The LL-BFR group performed exercises with a 30-rep max while arterial occlusion pressure was applied to the thighs. The idea is to simulate the effects of training with higher loads while still only using lighter weights.
- The control group (CON) resumed their normal general physical activity without any additional resistance training.
- Researchers assessed changes in muscle and tendon volume using freehand 3D ultrasound.
The results
The researchers looked at the three separate muscles of the hamstrings (on the back of the thighs):
- ST — Semitendinosus
- SM — Semimembranosus
- BF — Biceps femoris long head
Here are the results:
- The high-load group experienced a significant increase in ST volume and improved knee flexor strength. Compared to the control group, there was no notable change in SM.
- The low-load blood flow restriction group experienced a smaller, non-significant increase in strength, however, they did have a significant increase in SM volume. Compared to the controls, there was no notable change in BF or ST.
- The control group didn’t experience any improvements in strength or significant changes in muscle volume.
- None of the groups had any changes in ST tendon volume.
The researchers reported large differences between participants, with some having greater muscle growth in ST, BF, or ST and others having a more balanced growth across all three parts of the hamstring muscle.
The takeaway
While this is a smaller study lasting 9 weeks, the results showed that a high-load program induced selective muscle growth of the semitendinosus while the lower load, along with blood flow restriction, promoted muscle growth of the semimembranosus.
When it comes to high reps vs low reps, this study shows that there are complexities and nuances within the varying parts of the muscles. More studies are needed on how high reps and low loads compare to low reps and higher loads in building specific parts of larger muscle groups over time.
The takeaway is that muscle-building is more complex among individuals and different parts of specific muscles. The control group that didn’t do any resistance training didn’t experience any improvements in strength or significant changes in muscle size, so resistance training is still the way to go.
