Tag Archives: Fiber types

Blueprint for big legs!

My old coaches used to say “The legs feed the wolf! There are few sports where having big, strong legs does not carry over into performance. Many people struggle to build leg size and strength while others have no issues at all. This post will discuss some factors which can influence growth of the leg musculature and how one can use this knowledge to their advantage.

Muscle is not all the same; there are several types and subgroups with different characteristics. Mostly when dealing with skeletal muscle we define the fibers as either Type 1 (Oxidative or Slow twitch) or Type 2 (Glycolytic or Fast twitch). Every muscle is made up of bundles of muscle fibers. Each bundle is from all of the same fiber type and innervated by a single nerve. The bundle and nerve assembly is known as a Motor Unit (MU).

Type 1 fibers tend to be smaller in size and produce less force. They also have excellent blood supply and mitochondrial density which makes them very efficient at oxidative metabolism. This means they don’t fatigue easily. Type 2 fibers are larger in size and more powerful. Unlike Type one they are not so efficient at oxidation and rely heavily on glycolysis, intramuscular ATP and Creatine Phosphate stores for energy. They are much more fatiguable than Type 1 fibers.

The recruitment of the muscle fibers is in order of size, from small to large. The rate and quantity of recruitment will depend on the activity. Slow, low force movements may only require a small recruitment of some type 1 fibers, whereas a heavy lift or sprint will additionally recruit a large portion of type 2 fibers.

When we are born we are genetically predisposed to having a larger distribution of one fiber type over another. With training we can influence a switch over, from one fiber type to another. The fibers will be persuaded to take on new characteristics rather than switch totally. In our earlier years of training and sport we have a large influence on the muscle fibers as they develop. In addition, our genetic makeup will naturally direct us into sports we are suited to physiologically as we are more likely to have success.

When we look at body parts and muscles, the fiber distribution can be influenced by the function. For example forearm muscles contain higher amounts of type one fibers, as grip endurance is required for relatively constant movement of hands and fingers. Legs are similar because we spend relatively large durations of time on our legs, walking and standing etc. For this reason legs will always have a relatively large amount of type 1 fibers.

Micro trauma to the fibers is the catalyst for growth. When we recover, micro tears in the fibers are repaired and the fibers become larger and stronger. Tension and metabolic stress are the two things that will cause stress and trauma. Time under tension (TUT) has long been regarded as a key factor in muscle growth. The more time a fiber is placed under tension the more damage created. In addition metabolic stress can also be quite effective at creating trauma. All we have to do is look at a track cyclist or sprinters legs to demonstrate this.

Putting this knowledge into practice is pretty simple. In order to successfully create hypertrophy in the musculature we must stimulate and cause trauma to both sets of fibers. The challenge with type 1 fibers is that they are harder to fatigue. They need higher volume to do this, and so a higher rep strategy should be employed. The challenge with the type 2 fibers is activation. Heavier and more explosive lifts are needed to activate and fatigue them. Lower reps with heavier weight, combined with some power and sprint training will be needed to promote growth of these fibers.

Tom Platz was famous for utilising high reps sets to produce bodybuildings most famous legs.

Tom Platz was famous for utilising high rep sets to produce bodybuilding’s most famous legs.

This not only applies to athletes but also to bodybuilders. The secret to growth is to cover all your bases and keep things simple and consistent. Using a combination of high and low rep training will provide a good overall stimulation making sure you are covering everything. When used as a part of a simple progressive training plan and combined with adequate recovery any athlete will build bigger stronger legs. The key point is to target the fibers effectively so they respond. If you rely on one technique exclusively it is unlikely that you will have long term success.

As with most training, athletes must try and learn their weakness and how to fix them. They can then target the issues with a balanced program to give them a well rounded base. The more familiar they are with the physiological factors involved the more effective a training program can be!

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Fat loss for athletes!

Body composition and body mass are important for most sports. The success of an athlete can rely heavily on falling within the norms of their sports, especially where a weight category is involved. Nutrition and training are both vital in the role body composition and weight management. I will not discuss dietary strategy as it is not my are of expertise. Instead I will discuss the training considerations and strategy.

Step one is for an athlete to identify whether he needs to reduce bodymass (weight) or reduce body fat. Bodymass deals directly with bodyweight on the weighing scale with no concern for body composition. Body fat deals with body composition with possibly no influence on overall bodymass. When reducing body mass the main focus, is to create a consistent calorie deficit. How one trains doesn’t really matter as bodymass will decrease over time if calorie expenditure exceeds consumption. The issue is that this reduction will not be selective in terms of tissue loss. Both muscle and fat tissue will be lost but this is not such a good thing. In many cases an athlete will need to retain as much lean mass as possible and may even need to increase or at least maintain it. This creates a more complicated scenario where fat tissue must be the focus for reduction while avoiding any muscle tissue loss. The training strategy becomes a little more complex.

We know that in terms of metabolism, exercise at lower intensities utilise fat as fuel more effectively than high intensity exercise. The main drawback is that in terms of time efficiency it takes a relatively long period to burn sufficient calories. The other issue is that low intensity work can promote adaptations that are not so favourable for an athlete. Long periods of low intensity (LSD) training can promote a conversion of type 2 muscle fibers into fibres which more resemble the characteristics of type 1 muscle fibers. The athlete runs the risk of losing strength, speed and power. So this method must be used sparingly.

High intensity training has been touted as the magic pill for fat loss and performance in recent literature. Calorie expenditure is higher for a given work period and metabolism is elevated in the post training period. Sessions must, however be shorter as they will be more demanding. It is in this post training period where an elevated metabolism and active oxidative system plays its role in metabolising fatty acids. HIT may also promote strength, power and conditioning through a number of adaptive responses. At first glance this seems to be the obvious choice. As with most training methods it carries its disadvantages. By focusing on HIT we become reliant on the Glycolytic system during exercise. This system utilises carbohydrate metabolism and is always active even at rest when the oxidative system is dominant. Over time an athlete may promote the use of carbohydrates during metabolism which will in fact spare fat cells. If they do not consume enough carbohydrates there can also be a reduction in lean tissue as muscle cells do not get enough energy to survive.

The best strategy is to utilise both methods in an appropriate fashion. LSD can be made more effective in reducing fat and improving fat oxidisation by adding fasted LSD sessions into a program. Done before breakfast or immediately following a training session, enzymes active in fat oxidation must up-regulate to compensate for glycogen depletion. This means that less time is needed to initiate fat oxidation. HIT should then be performed in a fuelled state in a separate session to make use of its benefits. When both types of sessions are used in a balanced way that does not impede the athletes recovery, they can see all the benefits while negating the disadvantages.

As with most strategies a balance is required for optimum results. The body is exceptional at adapting to stress. Overemphasising one method over another will only display short lived success and may create problems in the long run. In the case of managing body weight and body mass a strategy must be formulated to suit the needs of the individual. A gradual and monitored approach is best for achieving long term and consistent results.

Post Activation Potentiation

Also referred to as a PAP response, Post Activation Potentiation has been a tool in an athletes training arsenal for decades. The basic theory is that if you lift a heavy weight you can perform a more explosive contraction soon after. So for example you might do a heavy double on back squat. Immediately after you may do box jumps or something similar and exceed expected performance. The underlying mechanism explaining this is actually quite simple. When you perform a heavy lift or contraction you must activate larger motor units to produce a more forceful contraction. These larger motor units are often referred to as type 2 muscle fibers. These fibers are generally larger and have greater capacity to produce force than smaller fibers. When activated they become slightly more sensitive to further activation for a short period of time after. When you go to perform the next contraction it will be relatively easier to produce force as these motor units are “excited”. Due to changes in sensitivity, the rate of contraction may also be significantly improved. This allows for a better power production overall.

Not a bad example to use. Photo by Hookgrip at www.hookgrip.com

Not a bad example to show. Big lift allows for a big jump!  Photo: Hookgrip at www.hookgrip.com

Not only can this PAP response be useful for improving power, it can also help improve strength endurance. I use the term endurance loosely there. It may allow you to perform more reps at sub-maximal loads without directly influencing fatiguing factors. For example, max repetition bench press is a common test used by many contact sport teams used during team physical testing. One or two singles close to max effort prior to the test can in fact improve the result. This is provided that the athlete does not go overboard and induce fatigue prior to the test. Often the athletes state that the weight initially feels lighter in comparison to a standard work up, warm up protocol. The PAP response can also be used in a hypertrophy program where back off or drop sets are being utilised. This is quite simply due to larger motor units being pre-activated, making a more effective use of available motor units, resulting in an improved performance. Larger volume in terms of weight lifted per session translates well into these types of programs.

While this is not a new concept or theory, the underlying mechanism is often overlooked and therefore under utilised. It is quite an effective tool and one which I have seen positive results from. Having an understanding of this concept allows a coach to be a little more creative in finding ways to help an athlete reach their potential.