The American Council on Exercise sponsored a research study “Is HIIT Resistance Exercise Superior to Traditional Resistance Training? A Randomized, Controlled Trial.” In this study performed at Western State Colorado University, Dr. Lance Dalleck and Leslie Smith examined the effects of traditional moderate intensity resistance training (MI-RE) versus high intensity interval training (HIIT-RE) on muscular fitness, cardiometabolic outcomes, and the timing of training adaptations.
This study took 48 nonsmoking males and females (age 21-59) and measured their strength on several different exercises before, during, and after the different training protocols were implemented (1-RM, 5-RM). Other health and anthropometric measurements were taken before and after the training protocols as well (resting heart rate, blood pressure, height, weight, waist circumference, skinfold measurements, and fasting blood lipid and blood glucose).
The participants were split up into three groups: HIIT-RE, MI-RE, and control. The HIIT-RE group performed 1 set of 5 reps at 100% 5-RM (the most weight that can be performed for 5 repetitions) on each exercise. The HIIT-RE group worked out twice a week for the first three weeks of the study and three times a week for the final three weeks. The MI-RE group performed 1 set of 10 repetitions at 60% 5-RM twice a week for the first three weeks and 2 sets of 12 repetitions three times a week for the last three weeks. The control group did not perform any resistance exercise.
The results of the study were as follows:
- For the HIIT-RE group, all measures of muscular fitness (1-RM & 5-RM) increased significantly from both baseline-to-midpoint and again from midpoint-to-6 weeks.
- In the MI-RE group, almost all 1-RM and 5-RM measures increased significantly from both baseline-to-midpoint and again from midpoint-to-6 weeks; the exceptions can be seen in Tables 3 and 4 (i.e., those exercises without asterisks).
- HIIT-RE elicited greater improvements than MI-RE for the following exercises and measures: seated row (1-RM and 5-RM), chest press (5-RM), leg press (1-RM and 5-RM), and lat pull-down (5-RM).
- HIIT-RE is equally effective as (and in some instances more effective than) traditional MI-RE at improving cardiometabolic health and muscular fitness.
- HIIT-RE improved muscular fitness in a more time-efficient manner, as it required less than half the time of MI-RE to achieve favorable adaptations. The average HIIT-RE session (including warm-up) was 20 minutes in duration while the average MI-RE session was 45 minutes in duration.
- Preliminary evidence suggests that HIIT-RE improves muscular fitness in a more rapid timeframe when compared to traditional MI-RE. Indeed, for a few MI-RE exercises (i.e., chest press and leg extension) there were no significant improvements in 1-RM and 5-RM values until after six weeks of training. In contrast, all 1-RM and 5-RM values improved significantly at three weeks in the HIIT-RE group.
The population used in this study reported no resistance exercise regimen within 6 months prior to the study, so the improvements seen in muscular fitness for both groups were to be expected. The greatest gains in strength are always seen at the beginning of a regular workout plan when neurological adaptations are the highest. With that being said, the quicker strength gains seen in the HIIT-RE group is important to highlight, as seeing these gains in only three weeks may improve the motivation levels of many clients during the early phase of a new workout. As we all know, it’s much easier to quit working out within the first month of your New Years Resolution due to frustration or lack of motivation.
Personally, this study validated the two biggest advantages to HIIT that I preach: time efficiency and cardiovascular benefits. By simply decreasing your rest intervals between exercises you spend less time in the gym staring at your phone and you save time spent on the treadmill or elliptical machines. That’s a win-win situation! As long as you have some kind of timer or personal trainer to keep you on track it is easier to keep up with than counting reps and sets in my opinion.
Here at MINDSET, we do HIIT workouts in our F.I.T. room (Functional Interval Training). While we vary the intensity of our workouts throughout the week, we also adapt them for all of our clients’ individual fitness levels. We are constantly modifying exercises and ensuring that everyone is able to physically push themselves the right amount without overexerting or hurting themselves. By individualizing our approach instead of giving everyone the same ‘blanket’ workout, our clients are able to meet their personal goals and make greater gains in strength, cardiovascular endurance, and overall fitness.
Avery Sullivan, CSCS