Optimizing exercise for health, muscle mass, and strength -a quick review of the evidence
For overall good health focus on achieving at least 150–300 min of moderate intensity or 75–150 min of high intensity aerobic exercise per week coupled with at least 2 days a week of resistance training. The most important factor in optimizing resistance training is RT itself and progressively increasing the work volume should be the focus. Minor variations in other RT variables (rest intervals, intensity, frequency), some supplements (protein, creatine, N3PUFA, Caffein and Nitrate) and pre-exercise dynamic warmup might offer minor additional gains in hypertrophy and or strength while static stretching prior to some forms of exercise (such as football, rugby, sprinting etc.) might reduce risk of musculoligamentous injury.
Exercise is undoubtedly one of the most important things we can do for our health, the question then becomes, how do we do it right? This short literature review aims to answer that question, it is based on evidence derived from reviews (systematic and unstructured) of randomized control trials as well as guidelines documents on the subject. Studies were identified by electronic searching the MEDLINE database as well as general searching through google and Bing search engines further supplemented by manual searching the references of relevant identified literature.
This document is intended to be practical and easy to understand, for more detail please refer to the cited literature. Additionally, most cited studies included healthy adult male subjects, therefore the information here is “most” generalizable to this target group.
1-Amount and type of exercise
2- What is moderate and high intensity aerobic exercise?
3- Optimizing resistance training for mass (hypertrophy) and strength gains
4-The role of Supplements
5- Stretching and warmup
Amount and type of exercise
According to the 2018 Physical Activity Guidelines for Americans and the 2020 World Health Organization guidelines for physical activity, adults should practice at least 150–300 min of moderate intensity or 75–150 min of high intensity aerobic exercise per week coupled with at least 2 days a week of resistance training. (1)
These are general types and amounts of exercise one should do in order to optimize health. The specific modality should be based on your particular preference, so explore and find what suits you!
What is moderate and high intensity aerobic exercise?
In aerobic exercise the large muscles of the body move in a rhythmic manner for a sustained period, leading to increased heart rate and respiratory rate. Intensity describes how hard someone is working during this type of exercise. Moderate intensity is equivalent to a brisk walk while high intensity is equivalent to running. It is worth mentioning that intensity can be measured in absolute and relative terms, with the latter considering the level of fitness of the individual while the former does not. A useful and simple way to estimate relative intensity is to do the “talk test”. Generally, a person doing moderate-intensity aerobic activity can talk, but not sing, during the activity. A person doing vigorous-intensity activity generally cannot say more than a few words without pausing for a breath. (2)
Optimizing resistance training for mass (hypertrophy) and strength gains
To optimize muscle mass and strength gains from resistance training the most important intervention is resistance training (RT) itself. (3) RT should incorporate both eccentric and concentric muscle movements with intensities of 40–80% one rep max (1RM), a tempo of < than 10 seconds per rep and with rest periods of > 120s (shorter rest seems to be adequate in untrained individuals). It has also been suggested that progressively reducing the rest period from longer intervals when a movement is being learned to shorter ones, thereafter, might offer similar benefits to long intervals (>120s) in trained individuals, while at the same time limiting the increase in overall training duration. (4–8)
The current body of evidence suggests that there is a graded positive relationship between RT training volume (sets X weight X reps) and muscle hypertrophy, with each additional set leading to an extra 0.37% increase in muscle hypertrophy and high-volume regiments (i.e., 10 or more sets) leading to an extra 3.9% in muscle hypertrophy compared to low volume regimens. However, the literature does not clearly suggest an upper limit of sets. (9)
Frequency of resistance training does not seem to have a meaningful impact when volume is equated, but higher frequencies could lead to higher overall volume and thus greater muscle mass gains. (10)
Alternative set structures (cluster, rest redistribution, etc), do not seem to offer any significant benefits in terms of muscle hypertrophy or strength. Although cluster sets might offer a minimal advantage in terms of explosive strength while traditional sets in terms of endurance. (11)
Although all these parameters are suggested by the current literature as being optimal for mass and strength gains, it is important to understand that they lead to a relatively small added benefit and the most meaningful factor continues to be doing some sort of resistance training and progressively increasing work volume.
The role of Supplements
There is strong evidence that Protein, Creatine and n3 Polyunsaturated fatty acids (N3PUFA) enhance the muscle mass and strength gains from RT. Caffein seems to enhance acute endurance and strength while nitrates effectively enhance endurance potentially leading to greater total work volume and hence enhance hypertrophy. (12,13)
Protein supplementation seems to enhance the effect of RT on muscle strength (by up to 9%) and mass (by up to 23%), with the effect being greater in younger, trained individuals. There also seems to be a plateau in this benefit above a dose of 1.62g/kg/day (CI 1.01–2.2). Additionally, it has been suggested that supplementation with whey protein and distributing the ingestion more evenly through the day may offer added benefits. (12)
Creatinine supplementation (at a dose of 0.3g/kg loading for 1 week, 0.03g/kg for 7 weeks) also seems to improve both strength and hypertrophy gains due to resistance training, with no clear evidence of harmful effects. (13)
N3Poylunsaturated fatty acids (N3PUFA)
Daily supplementation of 4 g/day with N3PUFAs (EPA1.86g +DHA 1.50g/day) has been shown to safely enhance muscle mass and strength gains from resistance training. This dose is approximately equivalent to the n–3 PUFA content of 200–400 g freshwater fatty fish (e.g., salmon, herring, and sardines). (13)
Strong evidence supports the acute strength and endurance benefits of low to moderate doses of anhydrous caffeine (∼ 3–6 mg/kg) consumed 60 min before exercise on muscle power and strength. (13) Although some consideration must be given to the timing of such supplementation as ingestion of Caffein within 6 hours of usual sleep time might interfere with sleep quality.
Multiple RCT have demonstrated increased muscular endurance induced by nitrate supplementation; this strategy may allow for higher training volume, and therefore, indirectly promotes hypertrophy. The dose that has been suggested to have such an effect is around 310–560 mg, which could potentially be obtained from the consumption of beetroot juice which is rich in this substance. (13)
Other supplements with questionable efficacy
Various other supplements have been suggested to have a positive effect on hypertrophy or strength, some of these include branched-chain amino acids, adenosine triphosphate, citrulline, β-Hydroxy-β-methyl butyrate, minerals, most vitamins, phosphatidic-acid or arginine, weak or scarce evidence was found for conjugated linoleic acid, glutamine, resveratrol, tribulus terrestris or ursolic acid (13)
For these supplements, the quality of the evidence is still insufficient for clear and safe recommendations to be made regarding their use. However future studies might shed some more light on their role.
Stretching and warmup
Although many studies have been done to investigate the effects of stretching on exercise related injury risk, the existing literature is of poor methodological quality and contradictory, however the consensus seems to be that it offers no statistically significant benefit in terms of overall injury risk reduction. Notwithstanding, some randomized control trials have shown a significant reduction in the risk of musculoligamentous injuries. (14–16) With some authors suggesting that due to this, stretching is of some benefit in exercises and sporting activities associated with frequent injuries of this kind, such as football, rugby, and sprinting. (17)
With regards to warmups prior to exercise the literature suggests that dynamic warmup strategies can improve strength and explosive performance (such as sprints). Studies tend to recommend a short active warm-up strategy (10–15 min), gradually increasing intensity (~ 50–90% of maximum heart rate). However, there is no clear evidence on the impact of warmups on injury prevention (18,19)
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