Astronauts lose 12-50% of muscular strength, and between 4-30% of muscle volume in space.[1,2] The loss occurs from the lack of loading due to being weightless. On earth loss of muscle mass can occur for many reasons, a common one is ageing. After 50 years of age most people see muscle mass decline by 1-2% a year, and strength decrease by 1.5% a year followed by 3% annual strength decreases after 60. Whether in space or on earth, this amounts to increasing limits being placed on our physical capabilities. I’m currently 48, and I plan to live to a ripe healthy old age where I can contribute to society as fully capable as possible, and hopefully in space too! To combat this, astronauts do 2 hours of exercise a day in space. Yes EVERY DAY. The exercise equipment on the International Space Station consists of a treadmill and cycle ergometer (bike) for aerobic exercise, and an Advanced Resistive Exercise Device (ARED) for weight training. Unfortunately, the current exercise protocols astronauts use do not prevent all muscle loss. More recently a high intensity training protocol (SPRINT) was shown to be more successful at preventing muscle mass loss in astronauts that the traditional slower, steady state protocols. I’ve recently been applying Dr Doug McGuff’s ‘Big 5’/Body By Science protocol of high intensity resistance training, which purports to provide all the exercise you need in 12 minutes a week. It involves doing 5 compound exercises, loaded sufficiently to correctly execute the exercise, yet heavy enough to bring you to failure after no more than 3 reps – reps done verrrrrrry slowly. Think 30 seconds for a single rep. I was initially a bit dubious, but also curious to see if I could maintain or increase my strength by sticking to the protocol. To add in some ‘cardio’ I did one HIIT or Tabata session a week – also under 12 minutes each time. And walked. I was surprised and delighted by the results of the six 12-minute sessions (a total of 72 minutes of resistance exercise) I did in a single month:
Seated row: 54% increase in strength
Chest press: 50% increase in strength
Underhand close-grip lat pulldown: 63% increase in strength
Overhead press: 33% increase in strength
Leg press: 41% increase in strength.
By exercising at greater intensity, we can achieve impressive results for the time invested.[6,7] The body adapts to the same exercise, as well as continued inactivity such as being weightless during spaceflight, so mixing things up using protocols such as this may be beneficial. Yet the comfort in having a regular exercise routine, and the psychological benefits it provides, made it mentally challenging to exercise so little each week. I will definitely use the slow-lift protocol strategically in my ongoing exercise regimes and will continue to use HIIT and Tabata protocols. I think they may provide health benefits when the idea of 2 hours of exercise a day is out of this world.
RH Fitts, DR Reily and JJ Widrick, ‘Physiology of a microgravity environment invited review: microgravity and skeletal muscle’, Journal of Applied Physiology, vol. 89, no. 2, 2000, pp. 823-39. Available: https://www.ncbi.nlm.nih.gov/pubmed/10926670
S Von Haehling, JE Morley and SD Anker, ‘An overview of sarcopenia: facts and numbers on prevalence and clinical impact’, Journal of Cachexia, Sarcopenia and Muscle, vol. 1, no. 2, 2010, pp. 129–133. Available: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3060646/.
JR Little and D McGuff, Body By Science: A Research Based Program to Get the Results You Want in 12 Minutes a Week, McGraw-Hill Professional, 2009.
JB Gillen and MJ Gibala, ‘Is high-intensity interval training a time-efficient exercise strategy to improve health and fitness?’, Applied Physiology, Nutrition, and Metabolism, vol. 39, no. 3, 2014, pp. 409-12. Available: https://www.ncbi.nlm.nih.gov/pubmed/24552392.
OR Seynnes, M de Boer and MV Narici, ‘Early skeletal muscle hypertrophy and architectural changes in response to high-intensity resistance training’, Journal of Applied Physiology, vol. 102, no. 1, 2007, pp. 368-73. Available: https://www.ncbi.nlm.nih.gov/pubmed/17053104.
VA Convertino, ‘Exercise as a countermeasure for physiological adaptation to prolonged spaceflight’, Medicine and Science in Sports and Exercise, vol. 28, no. 8, 1996, pp. 999-1014. Available: http://europepmc.org/abstract/med/8871910#.