High-intensity interval training has become a buzzword in the fitness world lately. Often abbreviated as HIIT, this cardio exercise takes many forms but yields surprising and enticing benefits.
Research indicates HIIT raises resting metabolic rate for up to 24 hours after exercise, burns more fat than steady-state workouts, and improves aerobic and anaerobic fitness.
HIIT workouts continue to rise in popularity because they produce great results, typically in less time than people spend on the treadmill or in an aerobics class. But, getting results from HIIT exercise requires following specific criteria to ensure safety and efficacy.
Planning a HIIT Workout
Because HIIT condenses maximum workout effort into a tightly packed training session, it’s important to have a workout plan before hitting the gym.
First, judge your fitness level to determine the length of your intense and resting intervals. If you’ve never done HIIT before, use a 1 to 4 work-to-rest ratio. For example, alternate between 15 seconds of intense cardio followed by 60-second rest period. If you’re in better shape, use a 1 to 2 ratio, or even a 1 to 1 ratio if you feel you’re already in near-peak shape.
Second, choose which cardio exercises you want to fill your high-intensity phases. Simple HIIT workouts repeat the same action for each phase. Examples include all-out sprinting or stationary cycling. More complex HIIT routines combine different movements to target more muscle groups. Try sets of lunges, burpees, jumping jacks, pushups, crunches or other exercises to add variety to HIIT workouts.
Third, decide the length of your workout. Fitness experts recommend starting with 15-minute training sessions. Then, gradually build up to 20 or 30 minutes. Exceeding 30 minutes of HIIT could trigger muscle wasting and isn’t recommended for non-professionals.
Last, make sure you incorporate warm up and cool down periods. It’s easy to skip over these essential steps because you’re eager to get to the “real” workout or just be done. But, warm up gets your blood flowing and stretches your muscles in preparation for exercise and cool down reduces risk of injury and relieves some muscle recovery side effects. After a high-intensity workout, you’ll want those benefits.
During a HIIT Workout
Enough with the planning! It’s time to experience HIIT for yourself.
In the middle of a HIIT session, pay close attention to your exhaustion level and your heart rate. HIIT is inherently more physically taxing than typical cardio exercises like jogging, even with the built-in rest intervals. Aim to hit 75 to 90% of your max heart rate during intense intervals. Stop and cool down if you experience difficulty breathing or chest pain.
Use your rest intervals to drink water and keep hydrated. You can optimize the effects of your planned HIIT workout with the following supplements. Research shows they positively affect high-intensity training.
For Before You Work Out:
Beta-alanine. This amino acid buffers muscle pH to minimize fatigue. Study participants who incorporated beta-alanine into their HIIT regimen increased total work done and had significant lean body mass gains.
For After You Work Out:
Protein or Amino Acids and Carbohydrates. Many people drink protein or carbs or both before a workout to enhance energy and muscle building. A 2012 study shows consuming carbs and essential amino acids after a HIIT workout raises IGF levels.
One HIIT workout boosts metabolism for up to 24 hours. But, like any exercise regimen, HIIT produces the biggest results when you stick to it.
Those looking to burn away fat should do 3 HIIT sessions per week, alternating days on and off. Muscle builders should do only 1 or 2 sessions per week, allowing at least 24 hours for muscle recovery before returning to weightlifting.
After you get into the HIIT habit, increase your intensity level every 1 to 2 weeks. There are numerous ways to amp an HIIT workout:
- Add more intervals to increase workout time
- Increase exercise difficulty
- Reduce work-to-rest ratio
Again, pay attention to how your body feels during and after HIIT exercise to ensure you aren’t being too weak or too intense. If you modify your workout but don’t feel like it’s adding any extra benefits, increase the intensity little by little until you notice a difference. Conversely, if your modifications cause your heart rate to remain elevated 30 minutes or more post-workout, reduce your intensity level.
Other Health Habits to Consider
HIIT is undeniably effective for reducing body fat and increasing cardiovascular fitness, but it’s not an all-in-one fitness solution. Maintain a balanced diet and limit splurging on junk foods to make sure you don’t cancel the effects of HIIT. It’s especially important to eat healthy carbs while doing HIIT exercises so your muscles have readily available fuel for their intense training.
For some people, 3 HIIT sessions each week provide plenty of exercise with a minimal time commitment attached. But, others like to augment overall fitness by adding in weightlifting sessions or endurance-based cardio. Some even do HIIT after their weightlifting sessions. Consider individual goals to make HIIT work for you—because HIIT will definitely make you work, but the rewards are well worth the effort.
-  Mayo Clinic staff. “Aerobic exercise: how to warm up and cool down.” 2011 Feb 26.
-  Kendall, KL, AE Smith, et al. “Effects of four weeks of high-intensity interval training and creatine supplementation on critical power and anaerobic working capacity in college-aged men.” Journal of Strength and Conditioning Research. 23.6 (2009): 1663-9.
-  Smith, AE, AA Walter, et al. “Effects of beta-alanine supplementation and high-intensity interval training on endurance performance and body composition in men; a double-blind trial.”Journal of the International Society of Sports Nutrition. 6.5 (2009).
- Foster, EB, G Fisher, et al.“Acute regulation of IGF-1 by alterations in post-exercise macronutrients.” Amino Acids. 42.4 (2012): 1405-16.