Speedendurance.com

Posted: 20 Dec 2010 05:00 AM PST

This is part 3 of a multi-part series. Part 1, which discussed hip mechanics, can be found here. Part 2 discussed several types of Resistance Running.

This article is guest blogged by Jim Hiserman, author of the books Program Design Method for Sprints & Hurdle Training and Strength and Power for Maximum Speed

How to Improve Acceleration: The Role of Strength and Power Training (continued)

In order for successful acceleration mechanics to be performed, the sprinter must execute a technically efficient and powerful start, so as to allow for the optimal body lean and posture necessary for a sound entry into the acceleration phase.

The role of Strength/Power Training in all phases of the sprint race cannot be underestimated. Any discussion of Acceleration Mechanics specific to teaching sprinters to properly execute the Acceleration Phase of the sprint race must take into account the relationship between proper mechanics and the strength/power required to do so.

In "The Mechanics of Sprinting and Hurdling" (Dr. R. Mann, self published, 2007), Dr. Ralph Mann points out several elemental relationships between strength and the ability to be more mechanically efficient or productive in the various areas/phases of the sprint race.

Dr. Mann cites three specific examples of this Strength/Mechanical Efficiency relationship affecting a proper Sprint Start and the ability to perform a successful acceleration phase.

Greater strength allows for the athlete to produce greater horizontal forces in the Start (pg. 52).
Greater horizontal force produced at the Start allows for the sprinter to stay lower at the Start (pg.52).
Success in the short sprint race is determined by the ability of the sprinter to generate great amounts of explosive strength at the proper time. (pg. 91).

Mann's analysis of sprinters found that weaker athletes tend to "pop up" during the Start because lesser amounts of horizontal force produced at the Start creates the need for the athlete to move the center of gravity vertically in order to maintain balance.

Given the need for the "falling or leaning" body position to properly execute a successful acceleration phase, block start mechanics must be incorporated into the drills used in teaching proper acceleration mechanics.

Glen Mills, coach of Usain Bolt and many world class sprinters, alluded to the role of strength in the acceleration phase (termed Drive by many coaches) in an interview where he echoed the statements by Dr. Mann; "…the athlete has to stay in the crouch position while developing maximum power. If the athlete does not have the strength to carry the drive phase long enough then it has to be aborted so he can go into the transition earlier."

Incorporation of relevant MAXIMUM STRENTH (also termed Static), EXPLOSIVE STRENGTH (also termed Dynamic) AND ELASTIC STRENGTH development exercises into the overall sprint-training program cannot be argued in view of the proven interdependence between Strength and the ability to optimally perform the proven principals of Sprint Mechanics in all phases of the short sprint race.

Since Part 4 of this Acceleration Article will deal with Elastic Strength (or Plyometric Training), this section will focus on Maximum Strength and Explosive Strength Training exercises proven to be relevant to proper execution of Start, Acceleration and Maximum Velocity phases of the sprint race.

Both Maximum Strength and Explosive Strength exercises must be used in order to address both Intramuscular and Intermuscular coordination factors. Through the proper mixing of Maximum and Explosive Strength exercises, Recruitment, Rate Coding and Synchronization can be optimally developed through use of exercises that coordinate the amount of force, speed of movement and precision of movement patterns applicable to effective sprint mechanics. Use of exercises that cover the entire Force-Velocity Curve, with an emphasis on moving the curve to left over time, cannot be done with a proper mix of Maximum, Explosive and Elastic Strength exercises.

There seems to be a considerable amount of confusion among coaches about the need for Maximum Strength exercises to be included with Explosive Strength exercises in the training of sprinters. The idea that lifting heavy loads in a relatively slow manner is of no use to the high speed movements of sprinters needs to revisited in light of the specific research findings provided in "Strength and Power in Sport", (P.V. Komi, IOC Medical Commission, 1992). Some of these specific findings are listed below.

High threshold Fast Twitch Glycolytic (FTb) Muscle Units are NOT recruited UNTIL force exceeds 90% of Maximum Strength (pg. 250).
Training with high velocity movements increases high velocity strength (pg. 263).
The load to be overcome and the movement time are the main factors in developing Rate of Force Development. If the load to be overcome is light, IRFD (Initial Rate of Force Development) predominates. If the load to be overcome is high, then MRFD (Maximum Rate of Force Dev.) predominates. For movements with a duration of 250ms or less (sprinting), BOTH IRFD and MRFD are the main factors (pg. 381).
Maximal Strength and Power are not distinct entities. Maximum Strength is the basic quality that influences power performance (pg. 383).
Improvements in Power have been shown to result from high intensity strength training, jump training under increased stretching loads and movement specific exercises requiring muscular coordination training (pg. 384, 385).
The use of training methods involving, maximal and near maximal contractions, cause a remarkable increase in RFD accompanied by an increase in movement speed (pg. 392).
RFD directed training should take precedence in the Preparation Phases but not be completely eliminated at any time of the training year (pg. 392).

Understanding the neural adaptations to the various strength training methods will allow for an intelligent selection of specific exercises and their proper integration into the overall training plan of each individual.

Strength/Power Training Plans must address the training age of the individuals within the sprint group. Beginning/Novice sprinters require different considerations than Intermediate and Advanced athletes. For example, research shows that Maximum Strength increases will also lead to increases in Power and the ability to generate force at fast speeds, especially in less experienced athletes. Training plans for Beginning/Novice athletes should contain more emphasis on Maximum Strength development and the teaching of proper lifting mechanics.

Each individual sprinter's needs vary according to body type, training age and current strength and power levels compared to their lean mass volume. Although all sprinters need a blend of Maximum Strength, Explosive Strength and Elastic Strength (along with Core Strength), the actual volume, intensity and frequency of each type of strength training needs to be adjusted for individual needs.

Athletes with high levels of Maximum Strength would benefit from a greater emphasis of Explosive Strength. Once Maximum Strength is elevated to optimum levels, it can be maintained with minimal work and emphasis placed on Explosive Strength and higher intensity plyometric (Elastic Strength) work.

Elastic Strength is also important to all sprinters but those sprinters who have lower levels of Maximum Strength would be exposed to injury if plyometric training at higher intensity levels is implemented without elevation of Maximum Strength to levels that allow for the increase of intensity in plyometric training.

Explanations and examples of the Neural and Physiological Adaptations of Maximum, Explosive and Elastic Strength Training Methods can be found in Strength & Power Training for Maximum Speed (Jim Hiserman, 2010).

Training plans for Intermediate and Advanced athletes, while not abandoning Maximum Strength, can mix in more Explosive Strength exercises. Maximum Strength is the pre-cursor to Power and any drop in Maximum Strength will bring a corresponding drop in Power.This is the reason that many researchers have advocated the continued use of Maximum Strength Training throughout the Training Year because the increased Rate of Force Development continues to be transferable throughout the entire range of the Force-Velocity Curve.

A better understanding for design considerations, based on training ages, can be found on pages 274-285 in "Principles and Practice of Resistance Training", (Dr. M. Stone, M. Stone, Dr. A. Sands, Human Kinetics, 2007).

Strength and Power Training exercise selection must take into consideration many other factors such as selection of: proper volumes, proper intensities, rest intervals and integration into the overall sprint-training sessions.

The difference between Maximum Strength and Explosive Strength training can be found in the load and speed of movement of the exercises. The following Foundational Strength/Power Training Exercises are categorized according to the specific types of (Maximum or Explosive) strength and their high correlation to sprint performance improvement.