If you’ve been reading this newsletter for a while, you’ll know I’m a strong advocate for measuring, maintaining and trying to improve VO2 max – which represents cardiorespiratory fitness based on the body’s ability to take up & use oxygen. You may have heard the term used to describe the incredible physical capacity of world-class athletes, but it matters for ‘normal people’. VO2 max. reflects overall physical health, representing many critical physiological systems working together.
VO2 max. values may even predict when someone is likely to stop being able to live independently in later life. For example, someone in the 10th percentile for VO2 max. could expect to begin relying on other people due to reduced physical capacity as soon as their early 70s. In contrast, someone in the 90th percentile could expect to remain independent for the rest of their life.
VO2 max. is so important that some clinicians argue it should be considered a vital sign alongside measures such as blood pressure. A recent study has added further weight to this claim, based on an updated meta-analysis of 37 cohort studies involving 2,258,029 participants.
Being in the top 1/3 of cardiorespiratory fitness decreases your risk of death by 45% compared to being in the bottom 1/3.
So how can you improve your VO2 max.? For sedentary people, it may be possible with very small amounts of activity. In 2019 researchers investigated whether a 2-minute workout could improve fitness relative to a control group with a sedentary lifestyle. Participants completed a 2-minute workout featuring three short 20-second intervals, three times per day, three days per week, for six weeks. The programme resulted in a 5% increase in VO2 max.
Longer duration, low to moderate-intensity training can improve VO2 max., but HIIT (High-Intensity Interval Training) can result in larger improvements in less time. Providing you don’t have any underlying health conditions to hold you back, here are three considerations for planning HIIT sessions.
Work-Recovery Ratio
Each ‘high-intensity interval’ may last from five seconds to eight minutes, performed at 80% to 95% of maximum heart rate. Recovery periods are usually at 40-50% of maximum heart rate. For example, you could begin with four to six 30-second sprints, each separated by 4-minutes of recovery. However, benefits are possible with various work-recovery ratios, so feel free to experiment.
Session Duration
A typical HIIT session lasts 20 to 60 minutes, but don’t let lack of time hold you back. In one study, 10-minute sessions featuring a series of 10-20 second all-out sprints improved insulin sensitivity by 28% and VO2 max. by 12-15%.
Frequency
Three short HIIT sessions per week for two weeks can improve VO2 max. and energy metabolism. Consider doing a few HIIT sessions back-to-back during time-pressed weeks. However, if you were to average over a month, aim for a distribution of approximately eight low-intensity sessions for every two high-intensity sessions.
The more you can increase your VO2 max. while you’re younger, & the better you can maintain it as you age, the longer & healthier your life is likely to be.
References
Laukkanen, J.A., Nzechukwu M. I., Kunutsor, S.K. (2022) Objectively Assessed Cardiorespiratory Fitness and All-Cause Mortality Risk. An Updated Meta-analysis of 37 Cohort Studies Involving 2,258,029 Participants. Mayo Clinic Proceedings. 97 (6). p. 1054 – 1073
Ross R, Blair SN, Arena R, Church TS, Després JP, Franklin BA, et al. Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign: A Scientific Statement from the American Heart Association. Vol. 134, Circulation. 2016. 653–699
Gries KJ, Raue U, Perkins RK, Lavin KM, Overstreet BS, D’Acquisto LJ, et al. Cardiovascular and skeletal muscle health with lifelong exercise. J Appl Physiol [Internet]. 2018;125(5):1636–45
Chudasama Y V., Khunti K, Gillies CL, Dhalwani NN, Davies MJ, Yates T, et al. Healthy lifestyle and life expectancy in people with multimorbidity in the UK Biobank: A longitudinal cohort study. PLoS Med [Internet]. 2020;17(9):e1003332
Milanović, Z., Sporiš, G., Weston, M. Effectiveness of High-Intensity Interval Training (HIT) and Continuous Endurance Training for VO2max Improvements: A Systematic Review and Meta-Analysis of Controlled Trials. Sports Medicine 2015; 45(10): 1469-1481
Metcalfe, R.S., Babraj, J.A., Fawkner, S.G. Vollaard, N.B.J. Towards the minimal amount of exercise for improving metabolic health: beneficial effects of reduced-exertion high-intensity interval training. European Journal of Applied Physiology 2012; 112(7): 2767-2775.
Gibala, M.J. & McGee, S.L. (2008) Metabolic adaptations to short-term high-intensity interval training: a little pain for a lot of gain? Exercise and Sport Sciences Reviews 36(2)p. 58-63
Seiler, K.S. & Kjerland, G.Ø. Quantifying training intensity distribution in elite endurance athletes: is there evidence for an “optimal” distribution? 2006; 16(1):49-56.
