High-Intensity Interval Training or HIIT is a great form of exercise where you workout intensively for short bursts of time followed by resting time.(1) However, there are so many people who are obsessed with HIIT and want to do it every day and it turns out they are overdoing it, because daily HIIT takes a toll on your body. It is highly recommended to perform HIIT not more than three to four times per week.
High-intensity interval training can be addictive, as you sweat out daily and get the toxins out and the happy chemicals going. High-intensity interval training is a form of cardio that is done for short amount of time with higher intensity than a regular cardio. High-Intensity Interval Training helps in building muscle and melting fat and this is the reason why many people get addicted to HIIT workouts; however, doing them daily is definitely not a good idea for your body.
When a person does HIIT, our body releases the stress hormone (cortisol); and this results in increased pulse rate, breathing rate, heart rate and blood pressure. For this reason HIIT is a good physical stimulator, as it stimulates the body’s fight-or-flight without the extra baggage of health issues.
However, even good things done in excess have harmful effects. Excessive of High-Intensity Interval Training causes your cortisol levels to sky-rocket and this along with various life stressors (pandemic included) puts the human body in a perpetual state of chronic stress resulting in diabetes, heart disease and weight gain.(4)
What happens exactly when you are performing HIIT workouts every day? What effects does it have on your body? Read on to know more.
The 5 Not So Good Effects of Doing HIIT Workouts Everyday
Overworking or Straining Your Heart
At its core, HIIT workout is a cardio workout and it increases your heart rate along with the oxygen demand in the blood. When doing HIIT, the heart works harder by pumping blood rapidly, as there is increase in the oxygen demand along with increase in heart rate and blood pressure. This increased cardiac output also can cause increased arterial dilation to increase the blood circulation.
The increased demand for oxygen when doing High-Intensity Interval Training followed by rest does help increase the efficiency of the heart function so the heart does a better job by pumping more blood with every beat and all of this lowers the strain and blood pressure. Other than this HIIT also increases stamina levels and energy levels, which helps cut down the risk of a heart attack. All these are the positive effects of HIIT for your heart; however, one should not do it every day and instead incorporate different types of exercises and not the same HIIT workout daily.
Always get a health checkup done especially if you are suffering from a heart condition before starting a HIIT routine. Upon any recommendation from your doctor, the intensity of the HIIT workout can be adjusted. Some of the signs that indicate you are overdoing HIIT and it is causing strain to your heart are: chest pain, shortness of breath and lightheadedness.(7) If you experience any of these symptoms, then it is time to consult your doctor.
Note: It is also recommended to use a heart rate monitor to help track your exercise intensity.
Difficultly in Recovering for Your Body
Without a doubt HIIT is an effective calorie crusher. After performing HIIT, your body experiences an after burn effect, which is also Known as EPOC or excess post-exercise oxygen consumption, as High-Intensity Interval Training creates an oxygen deficit. After performing HIIT, additional oxygen is needed by your body in order to get back to its normal metabolic state; and in trying to do so, it burns more calories about 24 to 48 hours after the HIIT is done. The greater the intensity of the workout, the more the need for the oxygen to recover and this means that your body has to work more to catch up even after you’ve left the gym or completed your HIIT workout.
When your body is in the after burn zone, it also burns or melts lot of fat. The aim of the high-intensity workout is to transition from aerobic to the anaerobic mode to burn fat.
A study in 2017 has shown that three weekly sessions of High-Intensity Interval Training greatly reduced the waist size and overall fat in obese people, same as when doing moderate-intensity exercise; however the difference being that HIIT is performed in lesser time with the same benefits of fat-loss.(5)
However, this doesn’t mean that you should do HIIT every day as excessive High-Intensity Interval Training causes injury from overtraining. Not just high-intensity exercise, but doing any type of exercise daily without adequate recovery time can cause metabolic issues, such as lactic acid buildup and overtraining syndrome, all of which can create a huge distance between your goals and you.(4)
Fatigue of the Fast-Twitch Muscle Fibers(3)
There are two primary muscle fibers: type I is slow-twitch muscle fibers; and type II is the fast-twitch muscle fibers.
When doing High-Intensity Interval Training, the fast-twitch muscle fibers get activated by the body. The type II muscle fibers are larger and denser and are used when performing powerful and short exercises, which can cause near exhaustion. Some of the classic HIIT movements include box jumps, burpees and cycling where type II muscle fibers are used. Fast-twitch muscle fibers help in quick generation of energy; however, they also get tired or fatigued easily and need adequate recovery time.
This is why one cannot just go on doing squat jumps continuously. After performing intense workout for some time, your body needs some seconds to minutes to rest and replenish the muscles before getting ready for another burst of HIIT.
As mentioned before the HIIT is cardio in essence; and using the fast-twitch muscle fibers helps with the growth and strength of your muscles and gives both strength as well as cardio benefits. But going overboard is not recommended, as it will cause muscle fatigue and injury. To give your muscles adequate time to heal, it is highly recommended to perform HIIT not more than twice or thrice a week.(9) Taking time off from High-Intensity Interval Training helps providing rest to the fatigued muscles and helps with their recovery. So, it is important to take a recovery day from HIIT workouts.
Your Joints Take a Beating
HIIT is generally safe when done in a correct manner; however, this type of workout carries inherent injury risks, as it typically consists of plyometric movements, which causes extra pressure on the joints.
Some of the common injuries resulting from HIIT workouts include: ankle/knee sprains; tendon/muscle strains. These injuries can also occur from doing other high-impact activities, such as jumping and running. Excessive HIIT also increases the risk of shoulder and back injuries, as it is linked with repetitive lifting or bending.
According to The Journal of Sports Medicine and Physical Fitness, many of the injuries incurred when doing HIIT-based exercises, such as burpees, result from lack of core strength, mobility and flexibility.(6)
To avoid any workout related injuries, it is extremely important to maintain good neuromuscular control or form; especially when one is exhausted. Always start your HIIT workouts slowly and gradually increase the speed. Proper stretching and recovery time are also vital to prevent exercise related injuries.
Injuries are more likely with HIIT as it puts your body through intense physical demand and the simplest solution to this is to avoid doing HIIT every single day. Instead, it is highly recommended to mix it with other types of workouts, such as strength training yoga and running. Along with change in the type of workout, it is also important to change the intensity levels to by changing the tempo, speed and the load.
Weakened Immunity from Daily HIIT
Research has shown that exercise helps with your immune system, however, too much of any exercise, particularly HIIT can backfire.
A study done in 2017 study in the Journal of Applied Physiology showed that performing high-intensity exercise without any adequate recovery causes decrease in your overall immunity, which in turn increases your risk for infection.(8) Continuing to perform High-Intensity Interval Training with a low or weak immunity makes you susceptible towards infection and other health issues.
A balance needs to be achieved between exercise and rest, so that the body is able to work at its best effectively as well as efficiently. It is important to have a balanced fitness routine compromising of rest, balanced diet, lots of water to keep your body healthy and to fight any sickness.
As High-Intensity Interval Training forces you towards maximum exertion with very less rest, it is important that you take recovery days between your HIIT sessions so your muscles can re-charge. It is sufficient to do HIIT workouts twice or thrice a week to reap its positive effects without hurting yourself.(9)
Conclusion: What is the Safe Way to Do HIIT?
Without a doubt, High-Intensity Interval Training or HIIT is great with amazing benefits; however, too much of it causes problems. A proper rest is needed between your HIIT session otherwise it can cause overtraining and injury. Daily HIIT workouts causes overworking of your heart, body, negatively affects the joints and also the constant soreness and fatigue leads to poor form and performance. So, even though you are working out, it is not benefiting you; in fact the opposite is happening.
Recovery time is as important as working out if you want to enjoy the complete benefits of any exercise routine. Recovery time is also important to avoid injury and to stay healthy. When your body and muscles repair and recover, then they are more attuned to the benefits from HIIT which become more concrete as you continue on this journey.
It is safe to conclude that doing HIIT two to three times a week is highly recommended and beneficial, doing more or doing it daily can cause nothing, but harm to you and your body.(9)