HIIT may sound like the latest dance craze sweeping the nation. In truth, HIIT has been known to do much more than dancing to Latino Music, Reggae, Classical or, for that matter, most dance forms. HIIT, also known as, High Intensity Interval Training is long been a part of the fitness community. Today, there are two reasons why HIIT has emerged as one of the most popular choices for fitness training, including:
People may obtain results through shorter workout sessions and this is valuable for many with busy schedules. Timmons demonstrated that three 20-second all-out sprints (same intensity) plus 60-second light recoveries performed three times for 6 weeks offers improved blood pressure, cholesterol and insulin resistance.
Tabata demonstrated that 7-8 x 20-second intervals (same intensity) plus 10-second light recoveries, four times a week for 6 weeks improved aerobic capacity (13%) and anaerobic capacity (28%) – better than a control group (60-min aerobic work 5 times week). Studies are almost endless in this area. Bottom line- you may obtain similar results from a control group program with up to 90 % less training volume and up to 67 % less training time.
The idea that HIIT promotes weight loss is possibly more of a perception than a reality. Still, it’s important to note that it is vital to never confuse maximal performance with maximal effort weight it comes to HIIT for weight loss. In addition, HIIT is not for everyone. Yet, read on if you want to learn more about HIIT.
• Maximal Performance has a distinct goal of improving performance. For example, if your recorded best 40-yard sprint time is 5 seconds, the goal is to improve that performance. To aim for maximal performance, each rep completed should be performed consistently within 90% of that time. Or, if aiming to increase maximal strength where 1RM (single best rep) = 100 lbs., then you may want to train at ≥ 90 % of that load to improve maximal strength (performance).
• Maximal Effort has a distinct goal of increasing sustainability of sub-maximal effort. In the fitness world, this equates to increased caloric burn. Consider this, if you continue to push as hard as possible under fatigue for that same 40-yard event, but completed it in 7-seconds – what is your purpose? Certainly not improved performance. Yet, you have sustained sub-maximal performance. Likewise, under fatigue, no longer lifting near 100 lbs., but now completing reps at 60 lbs., you may not be focusing on strength training, but now you’ll likely be focusing on endurance training. Now, the question becomes if fatigued and dropping intensity – isn’t your caloric burn rate also dropping? If so, could this not defeat the purpose of maximal effort training? Let’s explore the possibilities.
Our Energy Systems and Their Contributions
From an energy standpoint, let’s briefly examine our energy systems and their contributions, as follows.
• Bouts between 0 – 6 seconds = extremely high intensity (90 – 100% of maximal performance) = Phosphagen energy system (A).
• Bouts between 6 – 30 seconds = very-high intensity (80 – 95% of maximal performance) = combination of the Phosphagen (A) and Fast Glycolytic (lactate) (B) systems as A becomes depleted.
• Bouts between 30 – 120 seconds = high intensity (75 – 90% of maximal performance)= Fast Glycolytic system (B)
• Bouts between 2 – 3/4 minutes = moderately-high intensity (70 – 85 % of maximal performance) = Fast Glyolytic (B) and Oxidative systems (C) as B reaches its capacity lactate threshold). Keep in mind that this system is only good for around 2, perhaps up to 2 ½-3 minutes in women given the lower concentration of Type II (anaerobic muscle fibers) and influence of estrogen which interferes with this energy pathway and the conversion and clearance of lactate out of the muscle.
• Bouts beyond 3/4 minutes = moderate-to-lower intensities (< 70 – 75 % of maximal performance) = Oxidative system (C).
Also, keep in mind that rapid utilization of ATP to meet energy demand during B releases H-ions occurs. Pathway B (10 steps) also liberates H-ions that are usually transported to C, but when manufactured and accumulation of H-ions in B exceeds capacity to remove them, the muscle is faced with a challenge; that being a drop in pH (acidosis) which will shut down the muscle (H-ions = acidosis).
The body therefore manufactures lactate + H-ions to resolve this issue and passes both to blood. This action essentially allows the muscle to continue working, but the problem of acidosis (H-ions) is now inherited by the blood. Blood possesses a lactate + H-ion buffer and simultaneously regenerates it while utilizing, but when rates of buffering exceed rates of regeneration, we reach lactate threshold and only two options remain, including:
• Slow down to allow faster buffer regeneration (i.e., drop in performance, although individual continues giving best effort).
• Implement a low-intensity, active recovery (e.g., walking, stabilization exercises targeting type I fibers) to allow H-ion clearance from muscle and regeneration of lactate buffer.
It is also important to note that utilization of B is not only limited to local muscle fatigue, but primarily due to a generalized limitation in blood (inability to replenish buffer to handle spillover of lactate and H-ions). Even a well-designed high-intensity circuit, alternating muscle groups to spare individual muscles from energy depletion may still be limited to 2 – 4 minutes because of blood limitations. Unfortunately, this buffer needs time to recover – estimated 3 x time in recovery than in work to regenerate (light-active recovery to pump H-ions out of muscles). For example, 2-minutes of HIIT (> 75% of maximal performance) may need 6-minutes of recovery to be keep performance consistent across sets. So, if your bouts run 4-5 minutes with no-or-minimal recoveries (e.g., 15-second transitions); high-performance cannot be maintained, resulting in now training at sub-maximal endurance (HVIT), which is OK.
Yet, consider (a) technique decrement, (b) work-rate and calorie burn (low-intensity work or lower-tempo work does not burn many calories). Ask yourself, how do I keep work-rates up and provide for needed recoveries in order to perform HIIT? That’s easy, according to certified personal trainers. You may want to target type I fibers (aerobic) with stabilization exercises. You may want to challenge the body to preserve stability under fatigue – double-up your training benefits. Think of core and stabilization exercises to challenge stability under states of fatigue.
The Pro Fitness Example (> 75% IRM per exercise = HIIT)
The following example is not applicable for everyone. In fact, HIIT routines are highly individualized. A certified personal trainer may offer the best advice for you. Some people may require physician clearance for HIIT. The following is a Pro Fitness example for informational purposes only.
• Superset: Bb Clean and Press (45-sec; 5-second tempos = 9 reps) + Kb Side Lunges (30-sec / side, 4-second tempos = 7 each way) = approx. 105 seconds work: 1:3 = 315 sec recovery.
• Active Recovery: Walking = acute phase of EPOC (30-sec) + plank walk-ups (40-sec) + Rotational Planks (40-sec) + 15-sec transition, single-leg swings with hip drivers (3-planes) (40-sec / leg) + 15-sec transition; 12-16 Kg slow Turkish Get-up (40-sec / side) + 15-sec transition.
• Superset: Bb Deadlift (30-sec, 6-sec tempos = 5 reps) + Standing Kb Rotational Press (30-sec / side, 4-sec tempos = 7-8 reps/side)
While doing so, it’s wise to judge how tempo and intensity are maintained and modify recovery duration for subsequent sets.
Add to this the Kcal Differential
• HIIT example: 4-min x 5 sets (20 min) with 60-sec HIIT @ 20 kcal/min + 180 kcal recovery @ 5 kcal/min. Each interval = 35 kcal x 5, therefore total workout = 175 kcal.
• HVIT example: 2-min x 10 sets (20 min) with 60-sec HVIT intervals #1 – 2 @ 20 kcal/min + 60-sec recovery @ 5 kcal/min; but as work intensity drops – 60-sec HVIT intervals # 3 – 6 @ 17 kcal/min + 60-sec recovery @ 5 kcal/min; 60-sec HVIT intervals # 7 – 8 @ 12 kcal/min + 60-sec recovery @ 5 kcal/min; 60-sec HVIT intervals # 9 – 10 @ 9 kcal/min + 60-sec recovery @ 5 kcal/min, therefore total workout = 200 kcal.
• EPOC is influenced by intensity (first) and volume of work (second), therefore HIIT could have greater EPOC or both could be very similar.
Also, consider physiological differences between men and women. Females have lower concentrations of type II (fast-glycolytic) fibers (3.5 – 5.0 % less of these fibers than men), plus the influence of estrogen, including:
• Reduced glycolytic system capacity (reduced glycogen loading capacity = less glycogen; reduced glycolytic enzymes + reduced LDH (lactate dehydrogenase) activity to make lactate).
• Reduced phosphagen system capacity (reduced quantities of ATP-CrP and creatine kinase activity).
What this means is that intervals (individual or accumulated) performed as true HIIT should be limited to 2, perhaps up to 3-minutes, but recoveries can be shorter (1-2 work-to-recovery ratio) v. 1-to-3 for men.
The HIIT Summation
In short, drinking 6-8 eight ounce glasses of water each day helps to prevent strain on your body. Water can also help fill you up faster so you consume less food. So, seek out a favorite container and bring water with you wherever you go. When exercising and walking outdoors, know you need more water. Check in with a personal trainer to make sure you are getting the right amount you need for your work out.
Proper nutrition is also crucial to support a HIIT routine. Consider a physician recommended diet which will likely be filled with fruits, vegetables and protein. Seek out new foods and drinks, such as, vegetable juice. Spinach and salmon are great for a diet. A bit of honey, with its anti-oxidant properties for the aging, may help to inhibit free radical damage. It’s also critical to stay away from artificial sweeteners, corn syrup, high-sugar drinks and foods, hydrogenated fats, and white-flour products. Create a calendar for the types of foods you will have during each day. In this way, you can schedule planned meals with the right ingredients.
In the end, exercise allows your body to process oxygen much more quickly and efficiently throughout your body. In doing so, exercise helps support weight control, may diminish fat, reduces the risk of disease, enhances your mood, and offers a host of other benefits. Movement alone can wake up the body. If you have mobility or health issues, check in with your physician before engaging in any activity. If you are more of an outdoors person, seek out new interesting places to visit or exercise. And remember personal trainers are as popular as any trend today. So, visit your local fitness center and find out more about certified personal training.
It is important to recognize that all information contained on this website cannot be considered to be specific medical diagnosis, medical treatment, or medical advice. As always, you should consult with a physician regarding any medical condition. Your Health Access disclaims any liability for the decisions you make based on this information.