As many of you will know we recently surveyed our readers to discover what they wanted more of on our site. The response was fantastic and it gave us significant insights into the minds of our sports physiotherapy community. Subsequently, I know that many of you are interested in the world of triathlons.
If you are a sports physiotherapist that works with triathletes then you are all too aware of the potential for the development of overuse injuries. The triathlon is a grueling sport with distances ranging from Sprint distance (750 m swim, 20 km bike, 5 km run) through to the Ultra Distance or Ironman Triathlon distances (3.8 km swim, 180 km ride, and a marathon: 42.2 km run). No wonder many triathletes suffer overuse pathologies huh? This article discusses new research into the potential role of plyometric training in the injury prevention and rehabilitation of triathletes.
The Role of Aberrant Neuromuscular Control in Overuse Injury
As many of you would know, normal neuromsucular control is incredibly important in the maintenance of normal function. That is why many in the sports physiotherapy realm spend the majority of their day performing neuromuscular training activities. In the case of triathletes we are particularly interested because there have been established links between altered neuromotor control and overuse injuries, including:
- Patellofemoral pain (Cowan et al., 2002)
- Long-standing groin pain (Cowan et al., 2004)
- Low back pain (Hodges & Richardson., 1999)
- Exercise related leg pain when “running off-the-bike” (Chapman et al., 2010)
The Run Off The Bike Challenge
If you have undertaken any kind of triathlon training I do not have to talk to you about the challenge of running off the bike (in triathlon speak this means running following the cycle leg). This is a significant challenge to say the least. One reason why it is challenging is that cycling involves predominantly concentric muscular activation whilst running involves combined eccentric and concentric activation (Bonacci et al., 2011).
Riding Biomechanics (Concentric Dominant)
Runnig Biomechanics (Eccentric-Concentric)
Why Plyo Is The Go
It is hypothesised that the “stretch shortening cycle” utilised by plyometric training may lead to neuromuscular adaptations that will enhance running off the bike. This is a good hypothesis given that previous studies have reported plyometric and endurance training may improve:
- Running economy (Paavolainen et al., 1999; Saunders et al., 2006).
- Jump distance and force production (Paavolainen et al., 1999)
- Muscle recruitment patterns during jumping tasks (Lephart et al., 2005),
What Does New Research Tell Us?
Bonacci and colleagues (2011) investigated whether an 8 week period (3×30 min sessions/wk) of plyometric training could improve neuromotor control during running off the bike in those who it was aberrant. To do this they recruited 15 moderately trained triathletes, of which 8 were found to have aberrant neuromuscular control when running off the bike (i.e. significant change in EMG muscle recruitment patterns between pre and post-cycle running). The 8 triathletes were randomised into control (continue normal training) and an intervention arm (normal training plus an 8 week plyometric training program)
The plyometric program utilised was from a previous successful implementation of plyometric training in endurance athletes (Saunders et al., 2006). The exercises included:
- Knee Lifts
- Ankle Jumps
- Back Extensions
- Hamstring Curls
- Alternate Leg Bounds
- Skip for Height
- Single-leg Ankle Jumps
- Scissor Jumps
The primary outcome was obviously neuromotor control following running off the bike. Additionally they studied some secondary measures including running economy (i.e. sub-maximal V02 whilst running at 12km/h) and some anthropometric measures (including body mass, thigh girth, skinfold).
The study showed some positive results at the 8 week follow up as neuromotor control was corrected in 3/3 (100%) triathletes in the plyometric group compared to only 2/5 (40%) in the control group. The secondary outcomes, however, were not significantly different.
Limitations of the Study
There are a few limitations in the study, of which the authors are aware. We have the usual suspects including small sample size, participant and assessor blinding. Additionally, it is interesting to see 40% of those in the control group improved. This may suggest issues with the method or longer term repeatability EMG data collection.Furthermore, the improvement may have simply been related to an additional 90 minutes of training per week, given the inclusion of ‘moderately trained’ triathletes. Thus, this study requires validation in more highly trained triathletes.
Implications for Clinical Practice
- Clearly these findings are preliminary and there are limitations (as with all studies)
- These findings suggest that the addition of plyometric training to endurance training lead to greater improvements in neuromotor control when running off the bike
- This may have positive implications for injury management and prevention in triathletes
- The authors suggest plyometric training could be one of a range of modalities used in the prevention and/or rehabilitation of overuse injury in triathletes (Bonacci et al., 2011)
Bonacci J, Green D, Saunders PU, Franettovich M, Blanch P, Vicenzino B. Plyometric training as an intervention to correct altered neuromotor control during running after cycling in triathletes: A preliminary randomised controlled trial. Physical Therapy in Sport 2011;12:15-21
Chapman AR, Hodges PW, Briggs AM, Stapley PJ & Vicenzino B. Neuromuscular control and exercise-related leg pain in triathletes. Medicine and Science in Sports and Exercise. 2010;42:233-243.
Cowan SM, Hodges PW, Bennell KL, & Crossley KM. Altered vastii recruitment when people with patellofemoral pain syndrome complete a postural task. Archives of Physical Medicine and Rehabilitation. 2002;83:989-995.
Cowan SM, Schache AG, Brukner P, Bennell KL, Hodges PW, Coburn P, et al. Delayed onset of transversus abdominus in long-standing groin pain. Medicine and Science in Sports and Exercise. 2004;36:2040-2045
Hodges PW & Richardson CA. Altered trunk muscle recruitment in people with low back pain with upper limb movement at different speeds. Archives of Physical Medicine and Rehabilitation 1999;80:1005-1012.
Lephart SM, Abt JP, Ferris CM, Sell TC, Nagai T, Myers JB, et al. Neuromuscular and biomechanical characteristic changes in high school athletes: a plyometric versus basic resistance program. British Journal of Sports Medicine 2005;39:932-938.
Paavolainen L, Hakkinen K, Hamalainen I, Nummela A, & Rusko H. Explosive-strength training improves 5-km running time by improving running economy and muscle power. Journal of Applied Physiology 1999;86:1527-1533.
Saunders PU, Telford Rd, Pyne DB, Peltola EM, Cunningham RB, Gore CJ, et al. Short-term plyometric training improves running economy in highly trained middle and long distance runners. Journal of Strength and Conditioning Research. 2006;20:947-954.
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