Sports nutrition: fishing for strength gains

There are two types of essential fats for human health: omega-3 oils and omega-6 oils. These two types of fats are essential, because as well as being absolutely vital to build healthy cell membranes in our bodies, their chemical  structure means that they can also be used to make hormone-like substances in the body called prostaglandins, which go on to regulate a host of other functions. Although omega-6 can be synthesized from omega-3, the reverse is not true. This makes ensuring an optimum intake of dietary omega-3 oils especially important, especially as omega-6 oils are relatively abundant in the diet. EPA and DHA are two particularly important omega-3 oils as they provide a number of health benefits when consumed in the diet (and they cannot be synthesized in the body). Their long chains containing lots of carbon-carbon double bonds gives them the necessary shape and chemical reactivity needed to facilitate key metabolic functions in the body required for health.

Omega-3 and strength

Omega-3 oils are not building blocks of muscles so how is it that they might influence muscle growth and strength? Well, it turns out that when EPA and DHA are taken up into muscle tissue, they are able to help activate anabolic signalling proteins that are known to regulate muscle protein synthesis⁽¹¹⁾. In other words, they appear to help ‘switch on’ signals that instruct muscle cells to take up amino acids and incorporate them into muscle proteins. 

Good evidence for this comes from a study on fish oil supplementation (a superb source of EPA and DHA) in healthy young and middle-aged men and women⁽¹²⁾. This supplementation led to enhanced activation of a key signalling pathway known as ‘mTOR-p70s6k’, which in turn led to a 50% increase in muscle protein synthesis. Another study on resistance-trained young men demonstrated that EPA/DHA supplementation boosted the anabolic response produced compared to just feeding protein alone⁽¹³⁾. 

More generally, consuming EPA/DHA may positively influence several other mechanisms involved in resistance-training adaptations. These enhanced mechanisms include factors such as muscle fiber type transition, enhanced neurological recruitment of muscle fibers, reduced muscle protein breakdown, improved insulin signalling (helping amino acids to be taken up into muscle cells), enhanced muscle cell membrane function and the correct regulation of inflammation following training^(14-16). 

Real world strength benefits?

It’s clear that there are plausible mechanisms by which EPA and DHA ingestion can stimulate muscle protein synthesis. However, what is not clear is whether supplementing these oils enhances functional skeletal muscle outcomes - such as the promotion of actual muscle growth (hypertrophy) and functional strength - when resistance training is carried out. Some studies have been carried out that have produced inconclusive results, but these studies used very low doses of fish oils (under 1 gram per day) and didn’t monitor how much EPA/DHA was taken up by the muscles in the participants^(17,18). 

With this in mind, a brand new study by US researchers has investigated whether supplementing with more meaningful amounts of EPA/DHA (from fish oils) can help increase the strength gains, and muscle mass gains achieved from a resistance training program⁽¹⁹⁾. Published in the Journal of the International Society of Sports Nutrition, this randomized, placebo-controlled study looked at the effects of 4.5 grams per day of fish oil supplementation (providing a much larger dose of EPA and DHA) on resistance training induced adaptations following a 10-week training program carried out three days per week. 

The research

Twenty-eight young adults were recruited for the study, all of whom met the following criteria: 

• Aged between 18 and 40 years.
• Had not consumed ergogenic or fish oil supplements within six months of starting the study.
• Consumed less than two servings of fatty fish per week (ie did not already have a good EPA/DHA status).
• Recreationally trained with resistance exercise for at least six months and already familiar with the barbell back squat and barbell bench press.
• Were non users of other sports supplements or anabolic steroids. 

The participants were randomly split into two groups for the 10-week intervention:
1.    Supplemented with 4.5 grams of fish oil per day (containing 2.275 grams of EPA and 1.575 grams of DHA per day).
2.    Supplemented with inert safflower oil (the placebo group).

Participants in both groups conducted the same resistance program for the next ten weeks. This was a partially supervised full-body protocol on three non-consecutive sessions/days per week (two unsupervised and one supervised), consisting of seven exercises per session of 3-4 sets of 8-12 repetitions with 90-120-second rest intervals in between sets. Briefly, the following exercises were performed in the following order:

•    Barbell back squat
•    Leg press
•    Leg extension
•    Leg curl
•    Barbell bench press
•    Shoulder press
•    Seated cable row
•    Wide-grip lateral pulldown

The load was adjusted for all exercises based on each participant’s ability to reach momentary failure between 8-12 repetitions. The load was decreased at the next training session if the subject completed less than eight repetitions on the final set, or increased if the subject was able to complete all 12 repetitions on the final set. Before and after the 10-week intervention, all participants were assessed for lower- and upper-body strength. This was done by 1 rep max (1-RM) testing using the back squat and bench press exercises.

What they found

Twenty-one of 28 male and female participants completed the 10-week program. As expected, after ten weeks, the blood levels of EPA+DHA substantially increased in the fish oil group (by 109.7%) but did not change in the placebo group. The key findings however involved the strength level changes (see figure 2). After ten weeks the absolute strength levels in the bench press increased by 17.7% in the fish oil group but only 9.7% in the placebo group. Big differences were also seen in relative strength (strength per kilo of body mass); gains in the fish oil group were 17.6% but only 7.3% in the placebo group.

For the squat strength, the group differences were less pronounced. Absolute strength gains in the fish oil group averaged 28.8% vs. 20.5% in the placebo group (not quite a large enough difference to be considered statistically significant). However, in the relative strength test, squat strength increased by 29.3% in the fish oil group vs. 17.9% in the placebo group – a significant difference! A final finding was that in the fish oil group, there was a trend towards slightly lower fat mass after the 10-week intervention, which was not observed in the placebo group.

Figure 2: Absolute and relative strength gains in the bench press

Implications for athletes

We already know that dietary omega-3 intake tends to be sub-optimum in the general population^(20,21), and this is also known to be true for athletes too^(22,23). This is undesirable from a health and well being standpoint. However, what the recent research seems to show is that by optimizing cell signalling, the omega-3 oils EPA and DHA are able to maximize muscle protein synthesis. And now, for the first time, the above study provides strong evidence that an improved EPA/DHA intake can actually improve muscle mass and strength gains when athletes strength train.

Of course, this is only one study, so ideally further research will be needed to confirm these findings. In the meantime however, given that the majority of people consuming Western diets have a sub-optimum omega-3 status, and that a sub-optimum status is undesirable for a wide range of health reasons, there seems no reason why athletes involved in strength training shouldn’t increase their omega-3 intake – either via diet or using fish oil supplements. There are only potential gains to be had – and no downsides. Below are some practical tips for boosting your overall omega-3 intake. Remember however, the research above suggests it’s the EPA and DHA oils which are particularly important if maximizing strength is your goal!

Boosting omega-3 intake

·        Eat fatty fish twice a week; the omega-3 oils in fish are rich in EPA and DHA, which are especially beneficial. If you can get fresh mackerel, herring, sardines or unfarmed salmon and trout, so much the better – these will be free of chemical residues.

·        If consuming oily fish is difficult for you, consider taking a regular fish oil supplement rich in EPA/DHA.

·        Use fresh seeds sprinkled on salads, especially hemp, pumpkin and sunflower.

·        Use nuts in salads or mixed with raisins as snacks, especially walnuts, pecans and hazelnuts.

·        Switch to wholemeal bread – the wheat germ in whole wheat is a good source of omega-3. Likewise, use whole brown rice and wholemeal pasta instead of white varieties (the germ contains omega-3 oils).

·        If you can, use a cold-pressed seed oil in salad dressings (flax seed and olive blended makes a tasty combination), but make sure that it is fresh, has been packaged in a container that is also opaque to light and that the oil has been kept refrigerated since being produced.

·        Don’t rely too heavily on low fat/diet foods and protein/carbohydrate shakes for your calories – these are nearly all devoid of omega-3 oils.

·        Go for free range chicken and wild meats where possible – these generally contain higher amounts of omega-3 than their intensively reared counterparts.

·        Similarly, go for real free-range eggs if you can get them. Free foraging hens fed on natural foods lay eggs containing up to 30% of the fat as omega-3s.

References
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