Plyometrics

PLYOMETRICS: Four studies that you must read

This article will examine four key research papers on the benefits and sport-specific effectiveness of plyometrics training. We will examine their findings and place the results in the context of the wider peer-reviewed literature and expert opinion on the topic.

1) EVALUATION OF PLYOMETRIC EXERCISE TRAINING, WEIGHT TRAINING AND THEIR COMBINATION ON VERTICAL JUMPING PERFORMANCE AND LEG STRENGTH Fatouros et al. 2000, Journal of Strength and Conditioning Research.

Vertical jumping ability has been correlated with success in High Jump and linked to acceleration and sprinting performance (Schiffer, 2009; Marques & Izquierdo, 2014). Previous research has indicated that both plyometric and weight training may improve vertical jump height and maximal leg strength (Anderst, Eksten & Koceja, 1994, but the most effective training method remained unclear (Clutch, Wilton, McGown & Bryce, 1983).

This study examined the effectiveness of plyometric training, weight training, and a combination of the two for improving leg strength and vertical jumping ability.

The authors found that both plyometric training and weight training improved vertical jump height and leg strength compared to the control group, but a combination of plyometrics and traditional leg exercises achieved the greatest improvements in the selected parameters.

"The results indicate that long-term plyometric training is capable of improving vertical jumping ability, but its combination with weight training is even more beneficial"

Key Finding 1

One needs to be weight trained to enjoy positive adaptations to plyometric training

The participants in this study had not previously undergone plyometric training, but had enough previous strength training to be able to sustain the necessary plyometric loads. The metric that the researchers used was to only include participants who were able to back-squat 1.5 times their body weight.

The implication for coaches is that prior to commencing a plyometric program, you must ensure that your athlete has the required base strength to be able to handle the training load. This finding is supported by Ford et al. (1983), who found no improvement from plyometrics training in untrained High School students.

Key Finding 2

Training intensity, volume, and exercise selection should follow the principle of progressive overload

The authors attribute the successful outcomes observed for all treatment groups on the training model - starting with lower intensity exercises that worked single joints, and progressively increasing load and complexity. Training progressed from focusing on basic strength and exercise technique, to developing maximal strength and finally converting maximal strength to power.

The practical coaching implication is that exercises such as power jumps, snatches and push presses must be included in the training program to introduce power development once strength is sufficient (Bauer, Thayer & Baras, 1990)

Key Finding 3

A combination of plyometric training and weight training on the same day did not result in any adverse effects

The general consensus when this article was published was that plyometrics and weight training should not be performed on the same day. This has evolved over the years with further evidence to support ‘Complex Training’, - combined plyometrics and weights program (Ebben, 2002).

The practical coaching implication from this study was that complex training may be advantageous and that performing plyometric activities prior to weights ensured that participants were able to perform the drills with the proper technique and full explosiveness.

***VIEW FULL ARTICLE FOR EXAMPLE STRENGTH AND PLYOMETRICS PROGRAM USED IN THIS STUDY***

2) LOW AND MODERATE PLYOMETRIC TRAINING FREQUENCY PRODUCES GREATER JUMPING AND SPRINTING GAINS COMPARED WITH HIGH FREQUENCY de Villarreal, Saez Saez, Gonzalez-Badillo & Izquierdo, 2008. Journal of Strength and Conditioning Research

It is critical for a coach employing plyometric exercises to understand the optimal training load to maximise training efficiency and prevent overtraining. It is understood that in traditional weight lifting training that moderate volume of training at high intensity can produce greater strength gains than low and high volume (Gonzalez- Badillo, Izuierdo & Gorostiaga, 2006) but evidence for optimal plyometrics training load is limited.

This study examined the effectiveness of three different plyometric programs over a seven-week period - a 1 day per week program, a 2 days per week program, and a 4 days per week program.

The authors found that all three training programs improved 20 metre sprint time with no significant difference in the improvement observed between plyometrics program. Therefore, the 1 day a week program was found the most efficient for improving sprinting performance.

Jumping performance, as measured by a countermovement jump and drop jump, was significantly improved only in participants from the 2 days and 4 days per week programs. However, there was no signficant difference in the improvement observed between programs, making the two day a week program the most efficient for coaches looking to improve jumping height.

"The present results also showed improved sprint ability after short term plyometric training"

Key Finding 4

More is not always better - Significant improvements in speed can be achieved with lower plyometric training frequency

Significant improvement in 20 metre sprint time was achieved in just 7 weeks, using a training program that only trained for half an hour once a week with only 15 minutes of plyometric work.

The practical coaching implication for sprints coaches is that plyometrics may be most efficient when used in lower frequencies at higher intensities. This is especially important to know when you consider that the combination of plyometrics and traditional weight training is the most effective method to build leg strength, so it is important to achieve the best balance between the two methods of strength training.

***VIEW FULL ARTICLE FOR EXAMPLE PLYOMETRICS PROGRAM USED IN THIS STUDY***

EFFECTS OF A P LY O M E T R I C S INTERVENTION PROGRAM ON SPRINT PERFORMANCE Rimmer and Sleivert. 2000, Journal of Strength and Conditioning Research

This study has been selected as an important resource for coaches as it provides a proposed mechanism for how plyometric training may improve sprinting performance. In addition, this study provides an evidence-based training program that can improve sprinting performance using sprinting-specific plyometric exercises.

The study examined 32 representative-level rugby or touch rugby players who had no recent history of plyometric training. They were assigned to either a control group, a plyometric training group or a sprint training group.

The study found that plyometric training resulted in signifcant improvement in 40 metre sprint times and was equally effective as sprint training in improving speed. The increase in speed from the plyometrics group was not explainable by increased stridge length or stride frequency, but by reduced ground contact time.

"Sprint time over 40 m was significantly improved in the plyometrics group"

Key Finding 5

The effects of a sprint-specific plyometrics program appear to be greatest over the initial acceleration period (0-10m)

The authors attribute the improvement in sprinting performance noted in the plyometrics group primarily to the acceleration phase, where bounding exercises are likely to be most specific to running. This is believed to be because the two movements share similar ground contact times (longer than maximum speed running) and force production.

Conversely, the improvement in sprinting performance observed in the sprinting training group, was only observed between the 20-30 metre interval. This suggests that plyometrics and sprinting training may be improving different aspects of sprinting performance, supporting the argument for a combination of plyometrics and sprint training.

***VIEW FULL ARTICLE FOR EXAMPLE SPEED AND PLYOMETRICS PROGRAM USED IN THIS STUDY***

The longer ground contact times of the acceleration phase may closely match the movement of bounding

RESISTANCE TRAINING AMONG YOUTH ATHLETES: SAFETY EFFICACY AND INJURY PREVENTION EFFECTS Faigenbaum & Myer. 2009, Journal of Sports Medicine.

One of the challenges when coaching young athletes is identifying how to design appropriate conditioning sessions that develop physical competency in a safe and age-appropriate manner. Plyometrics have been demonstrated to improve speed (Meylan & Malatesta, 2009), balance (Paterno et al., 2004) and strength (Matos & Winsley, 2007), however there has been limited research on the effect plyometric training may have on short-term and long-term physical health.

This literature review analyses the safety and injury prevention effects of a range of resistance training methods, such as free weights, weight machines and plyometrics.

The study found that plyometric training is a “relatively safe and effective” method of training for children and adolescents, provided the loads prescribed are appropriate and progressed gradually over time.

"Advanced training programmes that include weightlifting movements andplyometrics are now recommended as part of performance-enhancing andinjury-reducing youth programmes"

Key Finding 6

For optimal performance and health outcomes, load should never be of an intensity, volume or frequency that exceeds the athlete’s ability to perform technically sound movements

The primary risk of injury from plyometrics was where the load was inappropriate for the developmental and training age of the athlete. The authors give the example of a 12-year-old boy who developed exertional rhabdomyolysis after performing over 250 repetitive squat jumps in a physical education class.

Coaches should employ gradual progression with young athletes and place a heavy emphasis on correct technique. If the load or intensity is ever at a volume where correct technique is compromised, the activity should be stopped and volume must be decreased to prevent injury.

Key Finding 7

Coaches must not simply super-impose an adult-based program on children and should avoid treating children as minature adults

Training Intensity for children should commence with low intensity drills and only when technique has been perfected and able to be repeated (including under fatigue) should children progress to more complex and intense exercises. Progression from low-intensity to high-intensity should be followed every session.

Faigenbaum & Chu (2001) argue that training volume should commence with single sets of 6-10 reps and progress to multiple sets of 6-10 reps. Recovery should range from 120 seconds to 300 seconds when performing high eccentric loads. For young athletes, plyometrics should be conducted up to two times per week on nonconsecutive days (Faigenbaum, 2006).

***VIEW FULL ARTICLE FOR YOUTH PLYOMETRICS GUIDELINES AND SUGGESTED PROGRESSION OF ACTIVITIES***

SUMMARY : YOUR TAKEAWAY MESSAGES

Major Finding 1

A combination of plyometrics training and traditionalweight training is the most effectiveness method toincrease leg strength and vertical jump height.

Major Finding 2

Plyometrics training onceper week was enoughto elicit a significantimprovement in speed andthere was no statisticallygreater improvement inparticipants training twiceor four times per week.

Major Finding 3

Plyometrics training can improve the sprintingperformance of an athlete, most likely as a result ofdecreased ground contact time.

Major finding 4

Plyometrics training is a relatively safe andeffective form of training for junior athletes.

Key Finding 1 An athlete may need to be adequately weight trained to enjoy positive adaptations to plyometric training.

Key Finding 2 Training intensity, volume, and exercise selection should follow the principle of progressive overload.

Key Finding 3 A combination of plyometric training and weight training on the same day, also known as ‘complex training’ did not result in any adverse effects

Key Finding 4 More is not always better - Significant improvements in speed can be achieved with lower plyometric training frequency.

Key Finding 5 The effects of a sprint-specific plyometrics program appear to be greatest over the initial acceleration period (0-10m).

Key Finding 6 For optimal performance and health outcomes, load should never be of an intensity, volume or frequency that exceeds the athlete’s ability to perform technically sound movements.

Key Finding 7 Coaches must not simply superimpose an adult-based program on children and should avoid treating children as minature adults.