Exercise is medicine, but have you ever wondered how much exercise is needed to heal the body?
The Instagram gurus and Men’s Health blogs may have you convinced hours of weekly exercise are needed to see results. It depends on the results you want.
Unfortunately, the guru and gym lore perpetuate a handful of myths that need to be debunked.
Myth #1 — You need to exercise a lot to see results
Having a structured exercise program is beneficial. For general health, the CDC recommends at least 150 minutes of moderate-intensity physical activity a week and two days of muscle-strengthening activity. You’ll find similar recommendations from other organizations. This is general health, however. In some cases, a single exercise can lead to great outcomes. For example, a recent study looked at how little exercise can be used to ward off surgery.
The QUADX-1 trial assessed whether home-based exercise therapy could prevent future knee surgery. They divided knee replacement candidates into three exercise groups. They all complete a single exercise — the knee extension (video example) — for either 2, 4, or 6 sessions a week.
Leg strength increased in all three groups, but that’s not the most interesting finding.
There was no difference between the three groups. Doing a single exercise only twice a week led to the same improvements in knee strength and greater improvements in knee pain and functional outcome questionnaires compared to four and six times a week.
Another study looked at the Nordic Hamstring Curl (see image below). To do this exercise, you need some method of pinning your ankles down. There are many variations too (examples).
While this exercise gained popularity as a method to reduce the risk of pulling a hamstring while running, new research suggests it can make you faster and more powerful. The most amazing part is the volume.
Across multiple studies, the Nordic hamstring curl improves sprint speed and hamstring strength with only 2 sets of 4 reps once a week. That’s it.
These studies do not mean pick one or two exercises to perform a week, rather, they show intentional exercise can be powerful. When I start a home exercise program for a patient, one exercise is often used to increase buy-in and improve the odds of sticking with it.
You have to consider goals. If you want to build muscle, for example, a couple of sets of one exercise a week will not work. But the narrative around how to build muscle is often flawed.
Myth #2 — There is a specific way to build muscle
Exercise should be specific to the goals you want to achieve. A training program for a marathon runner differs from a bodybuilder. Traditional gym lore and exercise programming recommendations suggest 8–12 repetitions per set is the ideal range for building muscle. It turns out, there is nothing special about 8–12 reps.
Research shows low load groups — often less than 60% of your one-rep max — result in equal amounts of muscle group as moderate load groups. High load — over 80% one-rep max — can have good short-term results but can lead to overtraining if relied upon for building muscle.
The keys are volume and effort. If you perform sets to or near failure, you stimulate the body to build muscle. Provided you have sound recovery strategies — a healthy diet and adequate sleep — the more you lift the better. If you are new to lifting weights, two sessions a week will do the trick. If you are experienced, 3–5 is more optimal.
These rules apply to everyone. It doesn’t matter the age or experience of the patient I see in the clinic. I often use reps in reserve to ensure adequate intensity is used on an exercise. If I am trying to stimulate muscle growth, I instruct patients to perform sets until they have one or two reps left in the tank.
Myth #3 — Only young people can build muscle
Again, the muscle growth rules apply to everyone. Increasing age does not prevent muscle growth.
A recent systematic review — meaning a study that pulled the results from many studies on the same topic — examined the effects of resistance training on muscle size and strength in very elderly individuals (greater than 75 years old). The study found the very elderly can increase their muscle strength and size by participating in resistance training programs. These effects were observed with resistance training interventions that generally included low weekly training volumes and frequencies.
For strength, the exercise programs lasted from 8 to 18 weeks with a training frequency of 1 to 3 days per week. For hypertrophy (a fancy term for building muscle), the interventions lasted 10 to 18 weeks, with a training frequency of 2–3 days per week. When looking exclusively at the oldest subgroup of participants (80 + years of age), there was a significant effect of resistance training on muscle strength as well.
To quell any concerns on safety, there were minimal reports of adverse events associated with the training programs. Provided the exercise is appropriate for the individual — training and health status — age should not be used to avoid weight lifting. This goes for the other end of the spectrum.
Myth #4 — It is dangerous for children to lift weights
First and foremost, lifting weights does not stunt growth in children.
One research review article pooled the results of 16 studies — including 1008 children age 7–12 years old — and found weight training had no impact on a child’s height. Conversely, studies show reduced fat mass, improved cardiovascular and metabolic health, and greater bone mineral density. That’s not all
Research is clear that resistance training is safe and effective for children and adolescents. That doesn’t mean open up the weight room and see what happens. Resistance training should be supervised — preferably by a trained professional such as a strength coach or physical therapist.
Every single child and adolescent who enters my clinic performs some form of resistance training. This includes body-weight exercises (calisthenics). One of the main kickbacks I receive — other than whether the body can handle resistance training — is children lack the motor control to handle the weight room.
This is not an all-inclusive list, but it is a strong start. Before accepting claims at face value, check the validity and the research.