This shoe offers and extremely thin stack height of just 4.8mm and is available with a matt microfiber upper.

Colour: White

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The all new 2011 model a-two has been given an all new design. As with the Vaypor the new a-two now has a lowered carbon height around the toe box area.

The model is made by hand from a combination of carbon fiber and fiberglass. The liner and outer skin are both made of light weight microfiber materials. This shoe has a stack height of just 4.4mm. The a-two is an extremely stiff shoe that allows you to get all your power down to the road. There is virtually no flex in this shoe whatsoever yet it remains comfortable due to our last shape.

Colour: White Matt

Price: £160 (SSP £190)

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Do you strength train for your chosen sport? And do you believe it makes you faster as well as stronger? If so, you could be barking up the wrong tree and might be better advised to work on your power.

Let me explain why. The figure below represents the theoretical relationship between concentric muscular force and muscle contraction velocity, or speed. Maximum force is generated by a maximal voluntary isometric contraction (MVIC), which has zero velocity. In theoretical terms, strength is defined as the maximum force of a certain movement. In practice, it is defined by the 1 repetition maximum (RM) load of an exercise in the gym.

The 1RM of a movement will produce slightly less force than the MVIC, as the 1RM is dynamic rather than static. To illustrate this by example, an athlete’s maximum squat may be 200kg, this being the weight he can lift, just once, with a maximum effort. At 201kg, the athlete would not be able to move the bar; however, if he applied max effort the MVIC force would be slightly greater than the force produced during the successful 1RM lift. Nevertheless, for the purposes of most coaches and athletes, it is fair to assume that 1RM is highly correlated with maximum isometric force.

In many cases, the aim of a strength programme is simply to increase maximum strength. Athletes typically train with weights between 75% and 95% of 1RM, and after a few weeks their 1RM scores go up, which is great because it means they are stronger. Or is it so great? Look at the force-velocity curve again and note that at the high force end of the curve the velocity of movement is at its slowest. Now think about how an athlete lifts very heavy weights – slowly. This is because it takes time – more than 400msec – to develop maximal force within the muscle: it cannot be switched on like a light.

Most athletic movements do not involve slow contractions at near maximum force, but are characterised by mid-to-high velocity. For example, the contact time of the foot during sprinting is about 100msec – not long enough to produce half of maximum force. This leads you to think about the benefits of strength training in relation to athletic performance a little more critically. What, you might ask, is the point of being stronger at slow speeds when most athletic movements involve high velocities?

Power – how to generate rapid force. A separate quality, quite distinct from strength, which can be developed with training, is power. In simple terms, power is the ability to generate force quickly; it is defined mathematically as force x velocity. If you look at the force-velocity curve once again, you will see that high levels of power will occur in the mid-range of either force or velocity. If an athlete develops greater power, this, in turn, enhances his ability to generate both force (strength) and velocity (speed).

This amalgam of speed and strength may be more useful for athletic performance than strength alone.

The above explanations of the force-velocity curve and the difference between strength and power raise two important questions:

1. Would an athlete benefit more from developing maximum strength or power?

2. What are the key differences between max strength training and power training?

For athletes who are inexperienced in strength training, any increase in maximum strength will tend to increase force across the whole velocity range of the force-velocity curve (1). This means that increases in maximum strength (greater 1RMs in the gym) will also lead to increases in power and the ability to generate more force at fast speeds. Indeed, research shows that maximum strength is strongly correlated with power, especially in less experienced athletes (2). This endorses traditional heavy weight training (75-95% of 1RM) as a way to improve athletic performance.

But research also shows that max strength development becomes limited beyond a certain point. Once an athlete has reached a high level of strength, any further increases will lead to improvement only at the high force/slow velocity end of the curve. This means no increases in power or force at fast speeds, which, as mentioned, is not necessarily desirable for most athletic movements. In a nutshell, as the athlete becomes more advanced and experienced in strength training, the effects of maximum strength training become increasingly specific to slow muscle contractions.

By contrast, power or ‘ballistic’ training has been shown to increase power and rate of force production and is more highly correlated with athletic performance than strength training. Power training methods can vary in terms of force and velocity characteristics, since the description embraces a number of different approaches. Plyometric jumping or throwing exercises tend to use higher velocity and lower force, whereas Olympic lifting exercises – eg power cleans – use higher force and lower velocity. Between these two extremes lie ballistic weight exercises, such a barbell squat jump and bench press throw, which employ moderate forces and velocity.

The benefits of each method differ slightly. To summarise simply:

Plyometric exercises promote high movement speed, fast twitch fibre recruitment and elastic tendon energy release.Olympic lifts involve very high power outputs, high rates of force production and increases in muscular co-ordination of whole-body movements, such as combined ankle, knee and hip extension.

Ballistic weight exercises are very useful for developing high power in specific areas of the body – eg arm extension power with bench press throws – and will result in high rates of force production and muscle activity in the specific muscle groups involved. There is a good logical argument for training with exercises at specific loads that produce the maximum amount of power for that particular movement. Power has been shown by research to be highly correlated with level of performance, and training which develops the maximum power output will increase force levels at the mid-to-high velocity end of the force-velocity curve.

Exercises of this type that I recommend frequently to athletes include power snatch, power clean, barbell squat jump, bench press throw and heavy bag rotation throw. These are all functional movements that involve moving moderately heavy loads as fast as possible. To generate maximum muscular power, a reasonable amount of load is required, and so these exercises involve greater power output than plyometric jumps, which use no additional load, or medicine ball throws, which are relatively light. Max power training is a distinct discipline and should be performed in addition to plyometric training, not instead of it.

Research has shown that the maximum power produced on a bench press throw or squat jump occurs with loads of around 50-60% of 1RM for the bench press or squat exercises. To develop max power levels in the legs and upper body, you can use 1RM test scores to determine the power training loads. For example, an athlete with 1RM scores of 200kg squat and 120kg bench press would produce max power on the squat jump exercise with a 100-120kg barbell and on the bench press throw with a 60-70kg barbell. Women may produce max power at slightly lower levels.

The importance of quality training

When performing a max power workout, 3-5 sets of 3-5 repetitions for each exercise would be effective. Power training must be high quality, as the aim is to recruit fast twitch fibres. For this reason, it is important to take at least three minutes rest between sets and to focus on moving the bar as quickly as possible. Max power training performed at less than max power simply does not work; coaches must encourage their athletes to hit each lift with max effort, while athletes must learn to focus on high-quality execution of the exercises. Power training is not like endurance training, where it is enough just to complete the session: it is how well you train for power that makes the difference.

With the Olympic lifts, such as power snatch and power clean, I have found that, for most athletes, maximum power occurs at slightly less than the maximum load. For example, if an athlete has a 1RM power clean of 100kg, then maximum power will be produced around 85kg. This is probably because most athletes do not have the time to develop the perfect technique and timing of elite weightlifters, and tend to produce a better speed of movement and coordination at less than maximum load. However, as technique improves the difference is likely to diminish.

There are great transferable benefits for athletes using loads for the Olympic lifts that produce maximum power for that lift. The athletes learn to feel the effort required for max power and speed of the lift and take this increased power into the sporting movement. This is my personal experience of the neural and coordination effects of max power training. Again 2-4 sets of 2-5 reps with long rests are recommended.

Many athletic movements, particularly throwing and kicking, involve trunk rotation. Rotational movements are not possible with barbell or weight machines, but standing rotation throws of a heavy bag (15-30kg depending on the strength of the athlete) are very effective at producing maximum rotation power, as they involve greater muscular force than medicine ball exercises. The same sets, reps and rest as above are recommended for effective training.

To summarise: the main difference between traditional heavy weight training and power training lies in the load and speed of the exercises. Loads of 75-95% of 1RM will result in increased maximum strength, while loads of 50-60% of 1RM, performed ballistically, will result in increased maximum power. Once an athlete has reached high strength levels, maximum power training may be more conducive to peak athletic performance than further increases in max strength.

Elite strength levels

How strong does an athlete need to be before the benefits of further strength training become limited? This depends on the individual athlete and his or her chosen event. For example, the shot put is significantly heavier than the javelin and may require higher max strength levels for success. As a guideline, elite levels of strength for a male athlete are 1RM squat of 2.5-3 x body weight and 1RM bench press of 1.5-2 x bodyweight, while those for a female are 2 and 1.25 x body weight respectively.

Once these levels have been reached, any athlete would probably benefit more from maximum power training than strength training. Having said that, there seems to be considerable benefit in combining the two methods within a periodised programme. A phase of maximum strength training followed by, or combined with, a phase of maximum power training is an approach supported by the literature.

The purpose of strength training

In writing this article, my aim has not been to diminish the importance of maximum strength training for athletic performance, but to make athletes and coaches think about a more complete approach to strength and power training in order to optimise performance. Remember that the purpose of strength training for athletes is not to increase 1RMs but to run faster, jump higher or tackle harder Improved performance is the ultimate goal, and power is highly correlated with performance – possibly more so than strength. It is logical to assume that training with exercises that produce maximum power outputs must produce improvements in rate of force production, muscle activation and functional coordination that are transferable to athletic performance.

Having said that, however, maximum strength is a precursor to power and needs to be developed to a sufficient level to maximise power production, particularly in stretch shorten cycle movements. Athletes who wish to continue to benefit from training programmes must vary their training. By incorporating both max strength and max power training into a training cycle, or periodisation, athletes can present their neuromuscular systems with a variety of different stimuli, so enhancing the adaptations.

References1. Strength and Conditioning Journal, 22(3), 65-76

2. Journal of Strength and Conditioning Research, 15(2) 198-209

3. Schmidtbleicher 1992. Training for Power Events. In ‘Strength and Power Training for Sports’. Komi et al

4. Journal of Sports Sciences, 20(12), 981-990

5. Medicine and Science in Sports and Exercise, 32(10), 1763-1769