With busy clients, I lean on short, smart bursts--think three sessions a week of 6 x 1-minute fast intervals (about 8 out of 10 effort), with 90 seconds of easy movement in between. For example, Monday, Wednesday, and Saturday you might do a 10-minute warm-up walk or jog, then your intervals, then cool down. After a couple of weeks, add a minute to two intervals, but keep the total work under 15 minutes so it stays doable and fun. The key is checking in on sleep, nutrition, and stress--sometimes it's smarter to repeat a week than push for more if your body feels off.
The most feasible VO2max microdosing program of busy clients during American Heart Month has been two 12 minutes interval sessions incorporated into the existing workout instead of introducing cardio days on their own. The structure stays simple. Following a five minutes warming-up, we apply 30 seconds hard with an approximate of 90 to 95 percent of maximum heart rate after which we spin or walk with ease 90 seconds. That is repeated four or five times. The maximum working time at high intensity will be less than three minutes, but the stimulus is high enough to shift VO2max with time. A sample week looks like this. The interval block is on Tuesday and Friday following the strength training. Targets on heart rate are verified using wearables, and perceived exertion remains in the range of 8 out of 10 on the hard work efforts. In RGV Direct Care, the focus lies on slow progression in which joints and tendons are shielded. Week three involves prolonging the length of a hard interval by one minute and maintaining the same recovery rate. The growth in volume is slow not to exceed 10 percent at any given time. After six to eight weeks, clients have quantifiable aerobic improvements, and do not experience the fatigue associated with long endurance workouts, with no injury rates being high, since intensity is constrained and controlled.