Economics is probably not something you associate with fitness. However, there is a concept from econ that may also apply to your workout — and learning it can help you ensure that every second you put into your exercise is helping you achieve your goals, rather than wasting your time.
If you didn’t sleep through Economics 101, you may recall the law of diminishing returns. Whether or not you recognize this term, the gist is: If you increase one factor of production (say number of workers) but not others (time, machines, etc.), the resulting profits, benefits or other positive outcomes slowly decrease.
In layman’s terms: You put in more effort for less results.
And when you think about that concept in terms of a workout, ain’t nobody got time for that. Luckily there are ways to avoid the law of diminishing returns when it comes to fitness.
HOW THE FITNESS LAW OF DIMINISHING RETURNS APPLIES
Given how HIIT classes have taken over the fitness industry, it’s common sense that we want to build the most muscle and burn the most fat in the least amount of time. And it turns out that your workout can be too long.
Take a squat, for example, says Miguel Aragoncillo, strength coach at Cressey Sports Performance. “Your first rep will theoretically be your best rep. You’re fresh, and your central nervous system is not tired or taxed,” he says. “But if you do the exercise repeatedly, by rep 100, your form will not be as good, you’ll be very slow, and you need to watch your upper back and joint integrity.”
Poor form, of course, means you’re not targeting the muscles you want to, which means you won’t get the results you’re aiming for. Plus you risk injuring yourself.
Worse, if you go too hard for too long, you may break down your muscle. While breaking down muscles is the point of a workout, you build muscle when it repairs itself post-workout. If your exercise keeps going and going, your muscles won’t have a chance to recover.
“That’s why runners and athletes use sports drinks,” says Jonathan Ross, spokesperson for the American Council on Exercise and author of “Abs Revealed.” “Carbs are your primary fuel for quick, explosive types of sports or activity. If you don’t replenish those carbs after about 90 minutes or two hours, your body can get into last-resort mode, breaking down muscle to turn it into carbs for fuel.”
Keep overdoing it without giving your body time to recover, and in about two to four weeks you can see an elevated risk of increased heart rate, disrupted sleep patterns, repetitive motion injuries and, in women, disruption of the menstrual cycle, Ross adds.
THE IDEAL WORKOUT LENGTH
So how long is too long? Like most things in life, it depends on many factors, including your fitness level, nutrition, injury history and sleep, Ross says.
However, there is some science to guide the length of a strength workout. “You have peak hormones at about an hour or an hour and 20 minutes of lifting weights. These hormones help your body adapt faster,” Aragoncillo explains. “So if you’re peaking around that time, what’s the purpose of doing a three-hour workout? Your results drop after that.”
Research also shows that after a certain number of sets, the benefit you get from an exercise slowly decreases as you continue to do more work. According to a 2009 meta analysis of 14 studies, you get 46% more strength benefit from doing 2–3 sets of an exercise than from doing a single set. However, there is little additional benefit if you do 4–6 sets.
“People sometimes think, ‘I have to save energy’ when they do four or more sets, so they don’t work as hard the first couple of sets,” Ross says. “It’s better to only do two sets but really go after it — and that doesn’t take as long either.”
WHAT ABOUT PLANKS? CAN YOU HOLD A PLANK FOR TOO LONG?
Plank-offs have become the new arm wrestling, a way to prove you’re tougher than the other guy or gal. But if you’re working to beat Mao Weidong, who holds the Guinness record of 8 hours and 1 minute, experts say don’t bother.
“If you watch the video, the first minute looks cool,” Aragoncillo says. “But he looks awful at the end — he’s just holding himself up and that’s not a plank.”
He recommends capping your planks at 60 seconds, while Ross suggests 30–60 seconds.
“The hardest part of a plank is a good takeoff and landing. Staying up and turning on all those muscles together,” Ross says. “Planks beyond 60 seconds is waste of time. Planks are great for core strength, but we have to do movement to develop fit bodies. Plus, for many people, isometric exercises maximize pain but minimize benefit. They burn the least calories because you’re not moving muscle. That also causes pain, because it limits blood flow, and blood carries away waste products of muscle contraction.”
HOW TO AVOID DIMINISHING FITNESS RETURNS
No matter what type of exercise you do, there are far better ways to make it more effective without working out for hours. “There are variables you can introduce to challenge yourself without diminishing returns,” Aragoncillo says. “Rather than thinking, ‘Can I go longer?’ think ‘Can I make this more difficult?’”
Try increasing your weight, changing your set/rep pattern, doing exercises at a different pace or holding a weight with only one hand to challenge your balance while strength training. For cardio, do intervals, increase the resistance on a machine or tackle hilly terrain if you’re outside.
As for the (not-so-) beloved plank, there are plenty of possibilities:
- lift one arm or leg
- shift your weight from side to side or front to back
- “walk” your plank from side to side or front to back
- place an exercise band around your arms above your elbows so you have to push them apart
- plank with your forearms on a stability ball (for added challenge, roll the ball in small circles in each direction)
- plank with your feet on a medicine ball
No matter how you choose to up your game, don’t forget to recover. “You make progress when you recover,” Ross says. “Your body needs time to rebuild from the stimulus of your workout. Otherwise you’ll get an overuse injury, hurt and quit.” And that’s the ultimate diminished return.
GEAR UP FOR YOUR NEXT WORKOUT