How hard should you push yourself to improve your fitness? It is a good question, one most people don’t spend much time thinking about. When I was a teenager and into my twenties, I didn’t give it much thought. I didn’t consider a workout to be successful unless I pushed myself to my absolute limit. Now, I know better.
Most people who exercise fall into one of two categories. The “go hard or go home” crowd that is constantly training to exhaustion. And the other category of exercisers is those who never push themselves hard enough. People who never push themselves won’t improve past the initial training adaptation, and people who constantly push themselves to their limits will produce better results, but this can lead to injury or overtraining if done excessively.
Training should take a systematic approach. Periods of over-reach need to be followed by periods of recovery. In this article, I will give you some simple rules of thumb to help you organize your training to elicit improvements without burnout.
Our body is stubborn and only adapts when it must. To elicit improvement, we must subject it to a stress that hasn’t been experienced before. For growth to happen, we must push beyond our comfort zone.
If you are new to training, your initial workouts will not have to be very intense to produce improvements. An individual new to cardio training could improve their fitness with brisk walks. Someone new to strength training doesn’t have to come close to muscular failure, the point where they fail to complete the next repetition to improve their strength and build muscle. But, after their body adapts to the initial stimuli, they will need to push harder to stimulate additional improvements.
Defining Intensity
Before we get into the specifics of training intensity, let’s define intensity as it pertains to strength and cardio training. In scientific literature, strength training intensity is often defined as a percentage of your one repetition maximum weight, but for our purposes, we will define it as our proximity to failure.
We will use Repetitions in Reserve (RIR) to define intensity. An RIR of three means you stopped three repetitions shy of failure. Your Rating of Perceived Exertion (RPE) would be a 7 out of 10, with 10 defined as performing as many repetitions as possible. Unfortunately, most of us aren’t good at judging our proximity to failure. So, you will need to take some of your sets to failure or very close to it to validate your RIR. I will discuss when and how shortly.
We will use Maximum Heart Rate (MHR) to measure cardio training intensity. There are several ways to estimate your MHR, but the simplest is to subtract your age from 220 heartbeats per minute. For example, the estimated MHR of the average 30-year-old is 190 heartbeats per minute.
A heart rate monitor provides an exact measure of intensity. But, you can estimate your heart rate by counting the number of pulses over 6 seconds and multiplying that number by ten. You can also use your Rating of Perceived Exertion (RPE) to estimate your training intensity; see the chart below.
How Hard Do You Have to Push Yourself to Improve
Most of your training should be submaximal but not easy. For adaptation to occur, training has to feel a little uncomfortable in order to force the body to adapt. The less discomfort you feel, the more training you’ll need to perform. For example, it has been my experience that one set performed to failure is as hard to recover from as three sets performed with two or three RIR. Similarly, for cardio, my RPE for a three-minute sprint is a seven or an eight, but my RPE for a 20-second sprint is a nine or a ten.
We have three primary levers to pull when it comes to producing stress. They are volume, intensity, and frequency. As you ratchet up one training variable, you must reduce one of the others. For example, when you take intensity to the limit, you must reduce your training volume. When you increase the volume of each workout, you will need to reduce your frequency. The key is finding the right balance to stimulate adaptation while avoiding burnout.
Strength Training
Another reason to avoid fatigue is that strength development is focused on neurological adaptations, not physiological adaptations. You want to train your motor units to fire quickly. As you get closer to failure, the weight will slow to a grind, which means your force production is decreasing.
You can stop most sets 3 to 5 repetitions short of failure for strength development, but for muscular gains, you need to train closer to failure. Lifting heavy weights is a skill, and like any skill, it is best developed when you aren’t fatigued. It is the reason coaches begin sessions with skill development and end them with conditioning drills.
Building muscle, on the other hand, is focused on producing physiological adaptations. Your goal is to force your body to build muscle by sending a strong enough signal. An untrained person can build muscle and strength with less effort than an experienced lifter because the stress is so novel.
As you get bigger and stronger, you’ll have to push yourself harder and harder. This is primarily done by adding more weight or performing more repetitions with the same weight. It can also be done by performing more weekly sets, but at some point, you’ll exceed your ability to recover.
As you approach your genetic sealing, you will have to increase your proximity to failure. You will have to occasionally go to failure to validate your RIR and produce further adaptations. The body must perceive these sets as life-and-death efforts that are necessary for your survival in order to dig deeper into its resources to allocate energy to building more muscle.
This type of training is mentally and physically exhausting and cannot be tolerated for more than four to six weeks without a break. I like to train my upper body muscles to failure one week and my lower body muscles to failure the next week. When I train to failure, I warm-up and then only perform one working set for each exercise. When I train short of failure, I perform three sets of each exercise, with 2 to 3 RIR.
When training to failure, it is a great idea to have someone spot you not just for safety but also for encouragement. Tell them your target number of repetitions and ask them not to assist you until the weight comes to a complete stop. Your spotter will help you dig deeper and push harder by cheering you on during your set.
You can take most isolation exercises to failure, but I wouldn’t take more than 30% of your compound exercises to failure and then only for about four to six weeks before taking a deload. A deload is when you intentionally train at a lower intensity to promote recovery, typically lasting a week or two.
I generally recommend taking your last set to failure to validate your RIR on your preceding sets and to avoid fatiguing the muscle too early in your workout, which would decrease the total number of repetitions you could perform. Once you exceed your repetition range on your last set, you will increase the weight during your next workout.
My recommendation to avoid failure on most sets is supported by numerous studies. A 2007 study by The Journal of Strength and Conditioning Research concluded, “Training to failure should not be performed repeatedly over long periods, due to the high potential for overtraining and overuse injuries.†Another study of lifters using loads 75% of their one rep max concluded, “Fatigue and metabolite accumulation do not appear to be critical stimuli for strength gains.â€
Taking sets to failure should be used as a means of creating progressive overload and evaluating your strength. It shouldn’t be a goal in and of itself. Progressive overload produces muscular growth, not training to failure.
Cardio Training
I recommend that 80% of your training time be spent at 70 to 75% of your MHR, an RPE of 7 or 8. Achieving a heart rate equivalent to 180 beats per minute minus your age should put your effort where it needs to be during steady-state cardio. For example, a forty-year-old would spend most of their time training at 140 beats per minute. This level of exercise is designed to build your aerobic base. It is sometimes compared to building your aerobic engine.
High-intensity interval training (HIIT) turbocharges that engine and is the best way to increase your VO2 max, the maximum amount of oxygen that an individual can utilize during intense exercise, and is considered by most experts as the best indicator of cardiorespiratory fitness. Sprints improve our ability to utilize oxygen by pushing our respiratory capacity beyond its current limits.
During sprints, you should feel a burning sensation in the muscles, which is the buildup of lactic acid and signifies you have crossed your anaerobic threshold, the point at which lactic acid starts to accumulate in the muscles. For interval training to be effective, you must exceed this threshold, also called your ventilator threshold. At this point, oxygen delivery to the muscles becomes a limiting factor, forcing your body to rely more on its anaerobic energy system. Your intensity should be between 80 and 90% of your MHR, an RPE of 8 or 9. These sprints should be followed by recovery periods at a level of exertion between 60 and 70% of your MHR.
Conclusion
Hopefully, this article has taken the guesswork out of how hard you need to train to see great results and achieve optimal fitness. These are my recommendations as a former Master Fitness trainer in the US Army and my decades of personal experience coaching others. But don’t let good be the enemy of great. I encourage you to make adjustments based on your preferences and goals. The more you enjoy your program, the more consistent you will be.
When it comes to fitness, consistency trumps intensity. If you don’t like intervals, you don’t have to perform as much as I recommend or any at all, but you should know that studies have shown that as little as three 20-second sprints performed three times a week has been shown to produce:
- Higher levels of fat oxidation in the muscles.
- Increased resting metabolic rate for up to 24 hours.
- Increased insulin sensitivity.
- Appetite suppression.
- Increased catecholamine levels.
- Spikes in growth hormone levels.
If you prefer interval training, you can keep your cardio sessions short and intense, performing 3 to 5 twenty-second sprints during short 5 to 10-minute sessions three times a week. If you don’t like strength training, performing as little as one set a week to failure will produce great results.
Remember that exercise is a dose-response; the greater the intensity of effort, the less volume and frequency are required to produce a stimulus for improvement. If you use a device like the Oura ring that indicates your readiness for training, you can use it to help decide when to push and when to ease up on your training intensity.
If I can help you, please email me at LeanByHabit@gmail.com.
Best wishes and best health!
Jeff
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