4. FORCED REPS
HOW IT WORKS To really boost growth factors, you need to train with balls-to-the-walls intensity. That means taking the last set of each exercise to failure...and beyond. A great way to do this is with the Weider Training Principle known as forced reps--research from Finland shows that they boost GH levels higher than when you end a set at failure.
Although the did not measure IGF-1 levels, the researchers reported that when subjects performed a workout using forced reps, their GH levels were three times higher than when they did a normal workout where each set ended upon reaching failure (higher GH levels typically mean higher IGF-levels in the circulation and/or in the muscles). In a follow-up study, the same research team found that trained men using forced reps recruited more fast-twitch muscle fibers, as well as more total muscle fibers during a workout as compared with when they used normal sets taken just to failure.
The forced reps also led to higher fatigue of both their muscle fibers and their nervous systems. The researchers suggested that this would likely result in greater muscle growth over time due to the increased mechanical stress placed on the muscle fibers and the higher release of anabolic hormones and growth factors induced by greater fatigue.
DO THIS: The key is how much help you get from your spotter. Too little assistance and you will not be able to complete an adequate amount of forced reps to stimulate muscle growth. Too much help will not adequately overload the muscle. The spotter must help just enough to get you past the sticking point but allow you to do the majority of the work.
You can still used forced-rep training even if you’re solo. Do single-arm or single leg exercises, and after reaching failure, assist yourself using your other arm or leg. Tempted to take every set to failure and do forced reps to boost IGF-1 levels higher? Don’t be. Spanish researchers found that men training for 16 weeks and taking every set to failure had lower circulating IGF-1 than those not taking sets to failure. Keep it to one set per exercise.