The original study (2007)
The best-known trial was run by Shinshu University and published in Mayo Clinic Proceedings (Nemoto et al., 2007).
- Who: 246 people (60 men and 186 women), average age 63.
- How long: 5 months.
- Groups: no training; moderate continuous walking (about 50% effort, 8,000+ steps a day); or interval walking (5+ sets of 3 minutes at about 40% effort and 3 minutes above 70%), each on 4+ days a week.
Compared with their starting point, the interval walking group improved:
| Measure | Change in the interval group |
|---|---|
| Knee extension strength (front of thigh) | +13% |
| Knee flexion strength (back of thigh) | +17% |
| Peak aerobic capacity, walking | +9% |
| Peak aerobic capacity, cycling | +8% |
All of those gains were significantly bigger than in the continuous walking group, and the drop in resting systolic blood pressure was also larger with intervals. The authors concluded that interval walking "may protect against age-associated increases in blood pressure and decreases in thigh muscle strength and peak aerobic capacity."
Worth knowing: not everyone in the study hit their training targets, and the numbers above are group averages. The 17% figure is leg strength, not blood pressure, a detail that is often misquoted online.
A larger follow-up (2011)
A later study from the same group (Morikawa et al., 2011, British Journal of Sports Medicine) followed 826 people around 65 years old doing the same routine for 4 months, and analysed 666 who completed all the tests.
Fitness and thigh strength went up, and body weight, BMI, body fat, blood pressure and blood glucose went down in every group. The people who started out least fit improved the most, which is encouraging if you're just starting.
Interval walking and type 2 diabetes (2013)
A small randomized trial in Denmark (Karstoft et al., 2013, Diabetes Care) compared 3-minute interval walking with continuous walking of the same energy cost in 32 people with type 2 diabetes, for 4 months (five 60-minute sessions a week).
- Fitness (VO₂max) rose about 16% with intervals, with no change from continuous walking.
- Body weight and fat, including visceral fat, fell only in the interval group.
- Blood glucose control improved with intervals; continuous walking prevented it getting worse.
It's a small study, but it supports the idea that how you walk matters, not just how much. If you have diabetes, talk to your care team before changing your exercise routine.
Why might intervals work better?
Steady, comfortable walking is great for health, but it may not challenge your heart and leg muscles enough to keep improving fitness. The brisk intervals push you harder for short periods, and the slow intervals let you recover so you can repeat that effort several times. Over months, that extra challenge appears to translate into more strength and fitness than the same time spent walking steadily.
What the research doesn't show
- Most participants were middle-aged or older Japanese adults; results in younger people may differ.
- The studies lasted months, not years. Long-term outcomes like heart attacks weren't measured.
- Effects are averages. Your own results depend on your starting fitness, effort and consistency.
- Interval walking is a fitness routine, not a treatment. It doesn't replace medical care.
References
- Nemoto K, Gen-no H, Masuki S, Okazaki K, Nose H. Effects of high-intensity interval walking training on physical fitness and blood pressure in middle-aged and older people. Mayo Clin Proc. 2007;82(7):803-811. PubMed · doi:10.4065/82.7.803
- Morikawa M, Okazaki K, Masuki S, et al. Physical fitness and indices of lifestyle-related diseases before and after interval walking training in middle-aged and older males and females. Br J Sports Med. 2011;45(3):216-224. PubMed · doi:10.1136/bjsm.2009.064816
- Karstoft K, Winding K, Knudsen SH, et al. The effects of free-living interval-walking training on glycemic control, body composition, and physical fitness in type 2 diabetic patients: a randomized, controlled trial. Diabetes Care. 2013;36(2):228-236. PubMed · doi:10.2337/dc12-0658
- Lee IM, Shiroma EJ, Kamada M, et al. Association of step volume and intensity with all-cause mortality in older women. JAMA Intern Med. 2019;179(8):1105-1112. PubMed · doi:10.1001/jamainternmed.2019.0899
- Paluch AE, Bajpai S, Bassett DR, et al. Daily steps and all-cause mortality: a meta-analysis of 15 international cohorts. Lancet Public Health. 2022;7(3):e219-e228. PubMed · doi:10.1016/S2468-2667(21)00302-9
This page summarises published research for general information. It is not medical advice.