Sports Medicine Research: In the Lab & In the Field: Fatigue Causes Decline in Lower Extremity Biomechanics (Sports Med Res)
Wednesday, June 12, 2013

Fatigue Causes Decline in Lower Extremity Biomechanics

Changes in Lower Extremity Biomechanics Due to a Short-Term Fatigue Protocol

Cortes N, Greska E, Kollock R, Ambregaonkar J, & Onate JA. Journal of Athletic Training. 2013, E-pub ahead of print. doi:10.4085/1062-6050-48.2.03

Take Home Message:  As the body fatigues there may be apparent compensatory strategies employed, however, lower extremity biomechanics deteriorate as fatigue becomes greater. This may have implications for injury prevention program implementation.

Lower extremity injuries (e.g., anterior cruciate ligament [ACL], ankle sprains) tend to occur later in games or practices when athletes may be fatigued; hence, fatigue may increase susceptibility to lower extremity injuries.  However, there is only limited evidence that fatigue influences lower extremity biomechanics. Therefore, the purpose of this study was to evaluate lower extremity biomechanics among female soccer players at two different fatigue severities during a functional task. Eighteen NCAA Division I female soccer players participated in motion analysis of a sidestep-cutting task and performed a functional agility fatigue protocol, which included vertical jumps, step-ups and step downs, and other activities. The authors assessed biomechanics pre-fatigue protocol as well as at 50% and 100% fatigue, which was defined by the inability to reach 90% vertical jump height during multiple sets or exertional heart rate plateau within 90% estimated maximum heart rate for 3 consecutive fatigue sets.  At 50% fatigue, the soccer players used more knee flexion during landing but at initial contact they used less hip abduction, knee-adduction moment, and hip-adduction moment. When the soccer players reached 100% fatigued they continued to use less hip abduction at initial contact, less knee-adduction moment at initial contact and less hip-adduction moment at initial contact; but, now they were also using less hip flexion and knee-adduction moment during landing. Interestingly, knee flexion decreased during initial contact and during landing even though at 50% fatigue the athletes were using more knee flexion during landing.

Clinicians should understand that fatigue affects lower extremity biomechanics. Therefore, injury prevention and rehabilitation programs should take this into consideration. Interestingly, the female soccer players may have adopted compensatory strategies at 50% fatigue (e.g., increased knee flexion angles during landing). This may be due to the familiarity of the functional tasks. However, as fatigue became more severe, these compensatory movements were abandoned for movements that may increase the risk of injury (e.g., less hip and knee flexion, knee adduction). This may point to a window of vulnerability.  Apparently these athletes can develop safe coping strategies up to a certain point, but they eventually will fail as fatigue gets worse.  This hypothesis may suggest that injury prevention, strength and conditioning, and rehabilitation programs could help train movement strategies; but, that we cannot ignore the importance of endurance in delaying maximum fatigue. Furthermore, our programs could include training during fatigued states. It will be interesting to see clinical trials testing whether these programs delay maximum fatigue or influence lower extremity movement strategies during fatigued states. In the meantime, we need to be cognizant of the obvious influence fatigue may have on movement strategies.

Questions for Discussion: Do you use injury prevention programs at the beginning or end of practice? Do you think that there may be more appropriate times for these programs to be implemented?  Has anyone had experience using cuing of biomechanics late in practices or games?
Written by: Nicole Cattano
Reviewed by: Jeffrey Driban

Cortes, N., Greska, E., Kollock, R., Ambegaonkar, J., & Onate, J. (2013). Changes in Lower Extremity Biomechanics Due to a Short-Term Fatigue Protocol Journal of Athletic Training, 48 (3), 306-313 DOI: 10.4085/1062-6050-48.2.03


Warren Potash said...

Since 1995, I have trained more than 600 teen female athletes to play every sport. I agree with this research since not one young women has ever had an ACL injury after training with our program.

I train the entire kinetic chain; especially balance, neuromuscular control and proprioception in fatigued states as the most difficult exercises are introduced as fatigue approaches 75% - 85% PE as part of sub-maximal and intervals for cardiovascular training.

By having these youngsters work hard and smart, their body is able to adjust to practice and playing demands since they worked harder in training than they have to work playing their sport.

Of course, a solid foundation must be established first before the advanced training can begin.

Nicole Cattano said...

Warren-Thank you for your comment. This is impressive clinical evidence. What age do you train the athletes? And how far out do you follow them through their careers? What type of a program are you utilizing?

TG said...

Analogously, I have seen a sort of biomechanical cuing in the late stages of wrestling practices. This was more from a performance standpoint, as opposed for the purpose of injury prevention, i.e. maintaining proper technique and body control in a fatigued state.
I do not think that it would be unreasonable to think that that skills taught in that fatigued state would transfer to being properly performed in the context of a live event, seeing as it appeared to have had a benefit for those wrestlers who went into the late stages of their matches. But, this is just an observation I have made over years of watching, participating, and coaching.

Bethany Rohl said...

I found this research to be very interesting. In my experience injury prevention programs are often implemented at the beginning of activity, often during the warm-up. However, with those current programs I do not think that fatigue was necessarily taken into account. It seems that teaching proper biomechanics in a fatigued state could have a greater benefit than completing the prevention program prior to activity. While there seem to be benefits to fatigued implementation, I would be concerned about poor biomechanics developing and then causing an increased risk for injury.

Nicole Cattano said...

Thanks to TG and Bethany for your comments. TG-were the wrestling skills loading or non-loading activities that were emphasized? I think you are absolutely right that it is anecdotally being done, but that perhaps more emphasis should be placed on it from a prevention standpoint.

Bethany-I couldn't agree with you more. But perhaps if we emphasize correct biomechanics in a controlled fatigued state, as opposed to an uncontrolled live activity state, there is the potential for carry over in a positive manner to live activity..

TG said...

Nicole= Basically all skills were emphasized, from non-loading take-down techniques where form was concentrated on in a slow progression individually, to skills that required lifts and throws. I suppose it really depended on the coach's practice plan for the day.

I agree about an emphasis being placed on the prevention aspect. I am very interested to see how this could be put in to use by athletic trainers and s&c coaches to possibly develop sport specific injury prevention programs.

Erin said...

I think the information from this research is important to take into consideration during our clinical practices. We usually have our athletes preform rehab before practice. I think this is important initially to learn the movement patterns in a controlled environment. However, the next step should be to put them through these exercises in a fatigued state. This is more game like and would only benefit them more in the future. Maybe practicing correct mechanics while fatigued will help the athlete when other forces are placed on their body during a game. I believe some clinicians understand this and try to put it into their practice; however, I think it needs to be used more often.

Nicole Cattano said...

Thanks TG for your response, and to Erin for weighing in. Erin (or other clinicians...), do you clinically have athletes perform rehab post-practice or in a fatigued state? I wonder what compliance would be like? I agree that it would be more game like, but how do you fatigue them prior to rehab?

Tony Pennuto said...

I am currently conducting a study analyzing the change in vertical ground reaction force pre and post fatigue. I will return and followup with results after I conclude the study. All the best - Tony Pennuto

Jacob Crow said...

Very interesting article that points out a lot of interesting points. I do agree with the comments listed above, it would be very interesting to switch the norms and move preventive rehab to post-practice or post-fatiuge. Obviously, compliance would play a huge role in effectiveness and quality of effort into rehab exercises. Another interesting thought, would be should we be altering the way that we define reps, sets, rest in between exercises in the clinical side. Often athletes are given exercises with reps and set (typically 3x10 is common) but are we missing an important element to a prevention program. Should we be instructing athletes to take minimal rest in between sets and increase the reps while coaching or instructing athletes on proper biomechanics as they fatigue during rehab exercises. Another interesting thought may be to increase load of exercises on a certain target muscle group and focus on that group during one training session to increase fatigue instead of performing a general strength program to the entire lower body or whatever you may be targeting. Obviously each day you would change exercises to focus on other muscle groups.

Nicole Cattano said...

Great point! I think part of the overall problem may be that we get "comfortable" with what has typically been done in the past and we need to focus more on what is the right thing to do, especially according to the evidence that exists. Jake's point about 3 sets of 10 is a prime example. We need to remember what our goal is and select sets, reps, rest ratios based on that goal. I wonder how Tony's study is going?

Nicholas Pables said...

This article was very interesting. Fatigued is a major factor in any form of competition, but is normally forgotten. I think staying after 30 mins after practice to go over form and technique would greatly help any individual lower their risk of injury. From my experience as a student athlete, I have noticed that the athletes, who did not work on their form after practiced while fatigued, loss their form during the game.

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