Getting stronger is simple: lift heavy stuff, put it down, and repeat. According to a new review led by researchers from the U.S. Army Research Institute of Environmental Medicine, you should use heavy weights that you鈥檙e capable of lifting one to five times through a full range of motion, and repeat for two to three sets a few times a week. That鈥檚 it. The rest is details.
Of course, the details are sometimes interesting鈥攅specially if you鈥檙e really trying to max out your performance, or returning from injury, or deployed somewhere far from the nearest gym. That鈥檚 what motivated the new review paper, which is by a team led by Barry Spiering, who was at USARIEM but has since moved on to a position as lead physiologist at New Balance鈥檚 Sports Research Lab. He and his colleagues tried to sum up what we currently know about how to get stronger in order to imagine how we might do better.
What Stimulates Strength Gains?
The opening section digs into root causes: what has to happen in your body in order to increase strength? Surprisingly, the first thing they identify is giving maximal mental effort. The bigger and clearer the signal your brain sends to your muscles, the more force you鈥檒l produce. And that signal-sending capability is trainable. Back in 2021, I wrote about a fascinating study in which locked-down pro basketball players gained strength by doing six weeks of completely imagined strength workouts three times a week. Similarly, lifting a light weight while imagining that you鈥檙e lifting a heavier one鈥攊.e. trying as hard as you can, even if you don鈥檛 need to鈥攑roduces greater strength gains.
Of course, strength isn鈥檛 all in your head. At the other end of the spectrum, using electricity to stimulate forceful muscle contractions also leads to strength gains, even though that requires no mental effort at all. In this case, it鈥檚 the muscle fibers and neurons themselves that adapt. So a training program that鈥檚 both mentally and physically challenging is the best of both worlds. Spiering also argues, based on the literature, that exercises should include both lifting and lowering the weight, and should move through a full range of motion.
The final point is more controversial: does metabolic stress in the muscles trigger strength gains? Endurance athletes know that hard exercise triggers a rise in lactate in their muscles, but that鈥檚 just one example among many: by one count, at least 196 metabolites rise or fall after a workout. One line of evidence that metabolites matter: blood-flow restriction training, which involves putting a blood-pressure cuff on your arm or leg while you lift, traps those metabolites in the limb and enhances the response to what would otherwise be easy exercises. Not everyone is convinced that metabolites matter for strength, but it鈥檚 an area of active research.
How Can We Exceed Current Limits?
Given what we know about how to stimulate strength gains, Spiering and his colleagues spitball some ideas for how to move beyond the usual lifting of heavy stuff.
One option is to lift heavier-than-maximal weights. This might seem impossible by definition, but there are a few possible workarounds. You could use electrical stimulation, either of the brain or of the nerves that activate the muscles themselves, to squeeze a little extra out of your muscles when you鈥檙e already pushing as hard as you can. You could take advantage of the fact that you can generate more force eccentrically (when you鈥檙e lowering a weight) than concentrically (when you鈥檙e raising it) by rigging up a system that gives you a heavier weight on the way down than the way up.
You could also figure out ways of amping up your mental effort during a lift that鈥檚 already at your physical limit. The weight itself isn鈥檛 heavier-than-max, but the neural effort鈥攁nd perhaps the resulting adaptations and strength gains鈥攁re. Alternatively, you could use mental imagery to add supplementary (but imaginary) workouts between your physical workouts, without delaying your muscles鈥 recovery from the last workout.
Biofeedback is another hot topic. Wireless EEG electrodes can quantify how hard your muscles are working, and show you the data on your phone in real time. This could help you push harder, or keep your effort in a target zone. Other technologies like muscle oxygen sensors could finetune when to stop one set, or when you鈥檙e recovered enough to start the next set.
What Can We Do Right Now?
Based on the ideas above, Spiering and his colleagues suggest a three-tiered approach to deal with specific strength-training challenges.
The first tier is no-load training, which is most relevant if you鈥檙e rehabbing an injury that prevents you from doing any physical training at all. One example, as mentioned above, is mental imagery workouts, where you imagine lifting weights in as much detail as possible. Another is opposite-limb training: if you have surgery on your left leg, you do exercises with your right leg. Since the brain signals for both limbs run along the same pathways, you get a 鈥渃ross-education鈥 effect that partly maintains strength in the injured limb. Finally, blood flow restriction might help, perhaps by elevating metabolic stress, even if you鈥檙e unable to train the limb.
The second is low-load training, which again could be useful during injury rehab and also works well if you don鈥檛 have access to a lot of gym equipment. There鈥檚 a robust body of evidence that lifting light weights can produce similar strength gains to lifting heavy weights, with the key caveat that you need to lift until close to failure. In other words, you need low load but high effort. There may be other ways of getting this effect, like where subjects lifted a light weight but imagined they were lifting a heavier one.
Finally, there鈥檚 the broad category of 鈥渟upplementary activities鈥: biofeedback based on EMG or other data; electrical stimulation; blood flow restriction. All have been the subject of promising research, but none is quite ready to be rolled out for general consumption with simple guidelines.
The takeaway? I still think the basics of strength training are straightforward. For most of us, in most situations, it鈥檚 probably a good idea not to overcomplicate it: lift heavy stuff and don鈥檛 worry about imaginary exercises or electroshock workouts. But the ideas above are worth remembering for situations where, for one reason or another, you can鈥檛 do a normal workout. And the one insight I鈥檒l keep in mind for all my workouts is the importance of mental effort. I鈥檝e always felt this intuitively, but it鈥檚 nice to know that being present and trying your hardest, rather than letting your mind wander, is a research-backed path to greater strength.
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