- Sports scientists signed up 60 male University of Zululand students who admitted being physically inactive smokers.
- Three times a week, one group did 20 minutes of high-intensity interval training on an exercise bike, while another did 40 minutes of continuous pedalling.
- Both groups improved their fitness after eight weeks, but the interval-training group was in much better shape.
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It’s the time of year when resolutions are often made about smoking and exercise, which means a young sport scientist’s first published research has arrived at exactly the right time.
And if you’re a physically inactive male smoker between the ages of 18 and 30, and wondering how to fit in some exercise that will have the greatest possible positive effect on your health in the least possible time, Nduduzo Shandu from the University of Zululand says he has the answer.
After putting 40 students who match that description through two eight-week exercise-bike regimes, Shandu says 20 minutes of high-intensity interval training is not only quicker but much more effective than twice the amount of continuous pedalling.
The group that completed three sessions a week in which they repeatedly sprinted for eight seconds then rested for 12 seconds improved their fitness, health-related quality of life and psychological wellbeing significantly more than the group that did continuous aerobic training in the same number of sessions .
In a paper published in the International Journal of Environmental Research and Public HealthShandu and his fellow authors from Zululand and the University of Essex in the UK say: “Our study suggests that high-intensity interval training may be useful in improving health and mental wellbeing, slowing the risks of onset and progression of smoking-attributable diseases , and indirectly prolonging life expectancy in smokers.”
To some extent, they say, this is not surprising because previous research has shown interval training can be adapted to different fitness levels, requires less time, is more engaging and enjoyable than continuous aerobic training and has greater physiological benefits.
In their study, however, interval training also improved lung function more than continuous exercise. Even so, both types of exercise led to improvements in the smokers’ lungs, measured by the amount they could exhale and the speed of exhalation, and Shandu says is the most striking finding.
Both groups also recorded significant improvements in recovery heart rate but the interval-training improvement was much greater. A measure known as rate pressure product, which is the product of heart rate and systolic blood pressure, also improved in both groups. This is regarded as a good indicator of the amount of oxygen the heart requires to work optimally.
About one in three South African men smoke, and Shandu says previous studies have found a third of students start smoking at university as part of a significant life transition.
That is why he decided to target smokers when he put up advertisements at UZ’s KwaDlangezwa campus in Empangeni and signed up 60 volunteers, splitting them into three groups.
Only two students dropped out of the interval training group, while four left the continuous aerobic training group before the eight weeks were up, and the control group – which had orders to remain sedentary for eight weeks – ended up with only 14 members.
The exercise groups completed 24 sessions on a stationary cycle ergometer in the UZ gym, starting with a five-minute warm-up and ending with a five-minute cool-down and 20-second stretches of the calf, hamstring, quadriceps, gluteus, back, neck and shoulder muscles.
It was in the middle of the workouts that things changed. The interval training group did up to 60 repetitions of a routine involving all-out sprinting then rest. Shandu says he increased the ergometer’s resistance for participants who completed two consecutive sessions. The sessions took a total of 33 minutes.
After warming up, the continuous aerobic training group spent 40 minutes cycling at 60 revolutions per minute and the resistance was altered to ensure their oxygen use was 60% to 75% of their bodies’ maximum capacity. Each session lasted 55 minutes.
“Findings suggests that high-intensity interval training should be the preferred form of exercise regime among college-aged smokers for more significant, healthier benefits,” says Shandu.
But he admits his study has limitations. “First, [it] consisted of a small, highly educated, homogeneous sample, which limits the generalisability of our results and the power to detect statistically significant differences.
“Second, the findings may not be generalizable to other age groups. However, [they] are consistent with previous evidence on the relationship between exercise and health fitness, health-related quality of life and psychological measures.
“Exercise is a vital component in decreasing the related risks of smoking-attributable diseases and can possibly increase life expectancy, which may be associated with physiological and psychological benefits.”