Isometrics - A muscle contraction with no movement, e.g. trying to deadlift an immovable object
1RM - The heaviest weight you can lift for a single rep
High Load - Typically Weights above 80% of your 1RM
Low Load - Typically Weights lower than 60% of your 1RM
Hypertrophy - Increases in the size of a muscle
I commonly get asked, "what set/ reps should I use to get bigger/ stronger/ faster etc"?or "how heavy do I need to lift to get bigger/stronger/faster"?
It is generally accepted that high load lifts are the most effective way to get strong, but there are ongoing debates on whether low loads can effectively improve strength and are high or low loads best for building muscle.
Strength increases are largely a neural adaptation, meaning your brain adapts the ability to control the muscle/ group of muscles in a co-ordinated fashion. This is why "newbie gains" is so easy to see. Your brain with each repetition learns how to become more efficient at co-ordinating the musculature to the desired movement outcome.
Hypertrophy increases are largely a structural adaptation, meaning the muscle fibers increase in diameter and the side by side structure of those fibers adapts to the way you are training them.
Schoenfield et. al (2017) released a review/ meta-analysis named Strength and Hypertrophy Adaptations Between Low- vs. High-Load Resistance Training: A Systematic Review and Meta-analysis.
The authors found that training with heavier loads leads to larger increases in 1RM strength, but there were still substantial increases achieved while training with lighter loads (less than 60% 1RM).
14 studies within this review looked at 1RM strength and unsurprisingly heavier loads were seen to be more effective at making increases. However, there was still an average measured 28% increase in 1RM strength using low loads (compared to 35% increases with high loads. Giving some confidence for the home gym trainer stuck in quarantine with only half the weight they are used to training with available.
Interestingly, the paper also found that over 7 studies, isometric strength improvement wasn't significantly different when training with high or low loads (22.6% for high load and 20.5% for low load). So our "raw potential" for the muscles to contract and produce force doesn't seem to need high loads to improve.
Finally, there were 10 studies looking into hypertrophy found close to a significant difference between low or high load training. But again not substantial enough to lose sleep over with an average of 8.3% increase in high load training vs 7% increases in low load training.
All this considered, there is potential that the adaptations occurring during strength performance are largely due to the organisation and coordination of the muscles firing in sequence.
So be patient my friends. When you first return to the gym after quarantine, you will feel weak, but have faith that it's just your brain feeling a bit confused and trying to remember how to do its thing.
Anecdotally, after a layoff of about 8 weeks, my squat progressions have looked like this
Week 1 - 165kg for 12 reps - Nearly died, could not do ANYTHING else that day.
Week 2 - 165kg for 12 reps - Comfortable, 3 sets of 4 all paused at 165kg afterwards and 3 assistance exercises.
Week 3 - 170 for 12 and full session afterward
Week 4 -175 for 12 - Small death, but struggled through the remaining session
Week 5 - 180 for 12 - Major death and I felt like my actual limit for strength.
I didn't improve my 12 rep max strength by 15kg in 5 weeks, it simply took my body 5 weeks to learn how to maximally train for sets of 12.
Give yourself the same benefit of the doubt when you first return to the gym. It's not your muscles, it's your brain!