Patients—and their doctors—would have to be living under a rock to have missed the memo that exercise is beneficial for health. We all know this, and yet, there are multiple barriers to actually doing it. For some, it’s time constraints. You have to go to the gym, change clothes, and possibly wait for certain pieces of equipment to free up. For others, it’s cost. Until gyms start handing out free memberships, the price tag can be an obstacle. And for others, particularly those with obesity, self-consciousness or fear of what others will think may keep them out of a gym or health club. Whatever someone’s reasons for not exercising, there’s good news: by working out intensely in the comfort of their own home, they can reap many of the same cardiovascular benefits they would get from a supervised program performed in a lab.
A study conducted at Liverpool John Moores University in the United Kingdom and published in the Journal of Physiology determined that obese individuals with elevated risk for cardiovascular disease (CVD) experienced similar improvements in multiple parameters whether they participated in a lab-based supervised high-intensity interval training (HIT) program, did a HIT program at home, or did home-based moderate-intensity continuous training that was virtually supervised.
The study was small (n=32) but adds to the growing body of scientific literature that indicates you don’t have to spend half your life in the gym to improve cardiometabolic health. Subjects completed one of three protocols: nine participated in the home-based HIT program, ten did the lab-based supervised HIT, and thirteen did the virtually supervised home‐based moderate‐intensity continuous training, all for 12 weeks. Muscle biopsies were taken at baseline and after the study training to assess changes in mitochondrial density, intramuscular triglyceride content, vascular enzymes, capillarization, and expression of GLUT4 (an insulin-sensitive glucose transporter in muscle tissue).
All three training protocols led to significant increases in VO2 max, whole‐body insulin sensitivity and flow‐mediated dilatation. There were also comparable increases in total eNOS (endothelial nitric oxide synthase) content in terminal arterioles and capillaries, and all measures of capillarization increased. The authors said it very clearly: “There were no between‐group differences.”
This is either good or bad news, depending on how people look at it. If time, money, and self-doubt or personal discomfort are obstacles to someone going to a gym regularly, now there are no excuses. They can reap the same benefits in a shorter time without having to leave home. No traffic, no funky gym shower, no weird guy flexing in front of a mirror taking selfies. Moreover, no equipment is required, not even an exercise bike or treadmill. (Feeling intimidated by complicated looking gadgets and machines may be another reason people avoid joining a gym.)
This study echoes findings we previously covered regarding a study out of Canada’s McMaster University that showed that among sedentary men, 12 weeks of a thrice-weekly ten-minute workout session—of which only one minute was high intensity—resulted in similar effects on insulin sensitivity, skeletal muscle adaptation, and VO2 max as a thrice-weekly session of 45 minutes of activity at 70% maximal heart rate.
Studies conducted by some of the same Liverpool researchers had similar conclusions. In a cohort of young men with obesity, a 4-week program of sprint interval training performed three times a week led to comparable improvements in aerobic capacity, insulin sensitivity and muscle capillarization as moderate-intensity continuous training performed five times a week. (It should be noted, though, that while both approaches improved glucose and insulin areas under the curve [AUC] and decreased resting heart rate, the improvements were slightly greater in the moderate-intensity group. It’s possible they would have been equivalent or closer to it had the sprint interval training been performed with equal frequency to the moderate intensity, but that is unknown.) Subjects’ weight, BMI and body fat percentage decreased but only slightly, which confirms what numerous other studies have shown: exercise can lead to cardiometabolic improvements even in the absence of significant weight loss.
Both of the UK studies involved cohorts of individuals with obesity, but similar results came from a study in sedentary young men without obesity (BMI 23.8 ± 0.7 kg/m2). Six weeks of endurance training (40–60 min cycling at ∼65% VO2 max 5 times per week) and sprint interval training (4–6 Wingate tests, 3 times per week) were equally effective for decreasing arterial stiffness and increasing skeletal muscle eNOS content and capillarization. Both cohorts experienced decreases in glucose and insulin AUC, but decreases were greater in the sprint interval group.
Recent meta-analyses comparing high-intensity intervals to moderate-intensity continuous training in subjects with type 2 diabetes or prediabetes echo all these conclusions: there’s little difference in outcomes between the two types of training but high-intensity training appears to have a slight edge with regard to VO2 max and cardiorespiratory fitness.
A systematic review and meta-analysis comparing the effects of sprint interval training versus moderate-intensity continuous training on body fat found that there were no differences between the two, and that, unfortunately, no clinically meaningful reductions in body fat were seen in short-term interventions (minimum 4 weeks). It’s possible that long-term exercise interventions, whether high or moderate intensity, would lead to clinically relevant decreases in body fat, but it’s also worth pointing out that exercise, by itself, is often not enough to reduce body fat to any meaningful degree, nor does it automatically guarantee good health.
With this in mind, whether they have obesity or not, people should exercise because it improves fitness and health (including mental health), and not because it’s an effective weight-loss tool. Depending on exercise alone to induce a significant change in weight or body fat is often a losing proposition, as many thousands of dedicated gym-goers can attest. But at least now we know they can do a short workout at home with no equipment and get some of those health and fitness benefits.