Improved VO2max: Why It Matters
The relationship between maximal oxygen consumption (VO2max) and cardiometabolic health is well-defined. Overall, the higher an individual’s VO2max, the lower the risk that person has for developing cardiovascular disease (CVD), coronary heart disease (CHD) and all-cause mortality (Kodama et al. 2009).
Kodama and team conducted a meta-analysis to identify the relationships between VO2max and CVD, CHD and all-cause mortality in more than 100,000 healthy men and women. The researchers looked at 33 studies that assessed VO2max via an exercise stress test, with results expressed in METs. (One MET, which is a person’s resting metabolic rate, is 3.5 milliliters of oxygen consumed per kilogram of body weight per minute.)
The scientists concluded that a 1 MET increase in VO2max is associated with 13% and 15% decreases in risk for all-cause mortality and CVD/CHD, respectively. The findings also showed that men and women with VO2max values of 7.9 METs or higher had substantially lower rates of CVD and CHD events. This large investigation clearly demonstrates that increases in VO2max lead to meaningful benefits for cardiometabolic health.
See also: Metabolism and Strength Training
3 Circuit Weight Training Workouts That Improve VO2max
For many clients, finding time to exercise for cardiorespiratory fitness and musculoskeletal health is challenging and often a barrier to exercise adherence, particularly during the COVID-19 pandemic. Fitness professionals regularly seek program design ideas that can optimize the health-related goals of clients in a highly time-efficient manner, and circuit weight training (CWT) may fit the bill.
Here are brief descriptions of three CWT programs—from actual training studies—that were shown to significantly improve VO2max. All three studies compared circuit training with another type of activity and a nonexercise control. For the purposes of this article, we’ll focus on the results of the CWT group.
CWT Study #1
Gettman, Ward & Hagan (1982) recruited 77 healthy men and women (average age 36) for this 12-week study. After extensive baseline screening for cardiovascular risk factors, participants were randomly assigned to three groups: circuit weight training (CWT), concurrent training (running and CWT), and a nonexercising control group. The CWT group trained 3 days a week during the study period using a circuit of 10 exercises that alternated between upper and lower body: squat, shoulder press, knee flexion, bench press, leg press, elbow flexion, back hyperextension, triceps extension, abdominal situp and vertical chest fly.
Participants performed all exercises at 40% of a 1-repetition maximum (measured every 2 weeks), completing 12–15 repetitions in 30-second sets, with 15 seconds of rest between exercises. A total of three circuits were completed during each session. In 36 sessions, the CWT group members increased their VO2max 12%–13% and made significant improvements in lower- and upper-body strength.
CWT Study #2
In a 3-month study, Piras et al. (2015) investigated the effects of circuit weight training versus high-intensity interval training. The CWT group comprised 10 healthy male and female participants (average age 24) who were recreationally active and free of any musculoskeletal and cardiorespiratory disease.
The CWT program consisted of six exercises performed in this rotational order: chest press, leg extension, latissimus dorsi pulldown, leg curl, shoulder press and seated heel raise. Participants performed 15 repetitions of each exercise at an intensity of 55%–60% of the 1-RM for that exercise. Subjects each wore a heart rate monitor and completed the workouts at 60%–80% of maximal heart rate. After performing all six exercises—with no rest between them—participants rested 1 minute and then repeated the circuit. Each session consisted of four circuits, and there were 30 sessions (on nonconsecutive days) in the 3-month period.
The CWT group showed an improvement in maximal aerobic capacity of 8%. >>
CWT Study #3
In another 12-week study, Kaikkonen et al. (2000) recruited 90 (male = 45, female = 45) middle-age, sedentary but otherwise healthy adults and randomly assigned them to endurance training, CWT or a nonexercising control group. The first two groups trained 3 days a week.
CWT participants performed three rounds of 10 exercises on air resistance machines, working for 40 seconds and then resting for 20 seconds. Intensity was fixed at 20% of 1-RM, with the number of repetitions performed at each station increasing throughout the study. Circuit exercises were leg extension, leg curl, abdomen curl-up, back extension, leg abduction, leg adduction, body twist right, body twist left, pushup and a pulldown exercise. Each participant wore a heart rate monitor and completed the workouts at 70%–80% of maximal heart rate.
After 12 weeks of training, the CWT group demonstrated an improvement of 11% in VO2max.
See also: Sample Class: Cardio-Strength Circuit
Body-Weight Circuit Training
To see if body-weight-only CWT could improve VO2max, Myers et al. (2015) recruited 34 sedentary but otherwise healthy college-age females and randomly assigned them to combined (traditional
resistance training and endurance exercise) (n = 17) or CWT (n = 17) training. The CWT participants exercised on 3 nonconsecutive days a week for 5 weeks, with just their body weight for external resistance.
Researchers provided repetition goals for each exercise. Participants were instructed to complete the circuit as many times as possible in a 30-minute period, with minimal rest. After 15 sessions, the participants in the CWT group had increased their VO2peak by 11%—a significant improvement. A key message from this study is that 90 minutes of body-weight CWT per week improves maximal aerobic capacity.
A Nontraditional Approach
Are there any unique variations of traditional resistance training that also improve VO2max? Haennel et al. (1989) recruited 32 middle-age males with below-average aerobic fitness and randomly assigned them to four groups: nonexercising control, endurance training, and two resistance training groups (explained, right). Participants trained 3 days a week for 9 weeks, with each workout lasting less than 30 minutes.
Unlike in circuit training, where enthusiasts rotate sequentially from station to station, in this study participants completed 3 sets of each exercise and then moved to the next station, following the traditional resistance training model. The exercises performed in each workout included the following movement patterns: knee extension, knee flexion, leg press, elbow extension, elbow flexion, chest press, shoulder extension, shoulder flexion and plantar flexion. For each exercise station, participants did 3 consecutive sets of the exercise, performing 20 seconds of work (for each set) followed by 20 seconds of rest. After the third set of an exercise, there was an 80-second rest before the next exercise.
One resistance training group performed the maximal number of repetitions (MAXrep) for each 20-second set. The second resistance training group performed 70%–85% of the maximum number of repetitions (SUBrep). The intensity settings on the hydraulic equipment were similar for the MAXrep and SUBrep training groups on all exercises. As intended, the SUBrep group performed about 14 repetitions per set, while the MAXrep group performed about 16 repetitions per set.
During 9 weeks of training, the SUBrep group increased their VO2max by 12.5% and the MAXrep group increased their VO2max by 11.3%. Uniquely, this nontraditional “rapid fire” approach to training elicited very favorable results for improving VO2max for both these groups.
A major take-away of this article is that people with higher VO2max capacities have more favorable cardiometabolic health and lower risk for cardiovascular diseases. That’s important information to share with your clients. The evidence-based workouts summarized in this article appreciably substantiate that creatively designed, time-efficient resistance training workouts can deliver excellent cardiovascular results. Get on it!
Common Characteristics of CWT Programs That Improve VO2max
The three CWT programs highlighted here—
all of which improve VO2max—have several training characteristics in common. For instance, they all include six to 10 exercises in a circuit that is repeated three to four times, for a workout lasting up to 30 minutes. Exercise intensities range from 30% to 60% of 1-RM. Rest between exercises range from no rest to 20 seconds. For participants wearing a heart rate monitor, it appears that a heart rate intensity of 60%–80% of heart rate maximum is maintained during the workout.
In all three programs, training takes place on 3 nonconsecutive days per week.
Source: Adapted from Myers et al. 2015.
Gettman, L.R., Ward, P., & Hagan, R.D. 1982. A comparison of combined running and weight training with circuit weight training. Medicine & Science in Sports & Exercise, 14 (3), 229–34.
Haennel, R., et al. 1989. Effects of hydraulic circuit training on cardiovascular function. Medicine & Science in Sports & Exercise, 21 (5), 605–12.
Kaikkonen, H., et al. 2000. The effect of heart rate controlled low resistance circuit weight training and endurance training on maximal aerobic power in sedentary adults. Scandinavian Journal of Medicine & Science in Sports, 10, 211–15.
Kodama, S., et al. 2009. Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women. JAMA, 301 (19), 2024–35.
Myers, T.R., et al. 2015. Whole-body aerobic resistance training circuit improves aerobic fitness and muscle strength in sedentary young females. Journal of Strength and Conditioning Research, 29 (6), 1592–1600.
Piras, A., et al. 2015. Peripheral heart action (PHA) training as a valid substitute to high intensity interval training to improve resting cardiovascular changes and autonomic adaptation. European Journal of Applied Physiology, 115, 763–73.
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