1. Please introduce yourself to the readers (how you started in the profession, education, credentials, experience, etc.).
When I went to the college for the first time, I started a BSc. on Math Sciences. In the mean time, I was practicing martial arts on a local gym for several years (I’m a Karate black belt) when, suddenly, the instructor had to left the classes and the gym owners needed to find another instructor as soon as possible. Since I was the most advanced student, they asked me to be the new instructor, and that was my very first contact with the world of training, which I became to love so much.
Maybe due to my math education, I wanted to make my trainings more scientific and research-based and, one day, I decided to quit Math Sciences to study Sports Sciences. My main interests was high-performance sports and resistance training so, when I finished my BSc. on Sports Sciences, I studied two MSc. on High Performance in Sports at the Spanish Olympic Committee and Pablo de Olavide University which were directed by the strength-training expert Juan José González-Badillo. Also, I got the NSCA CPT and CSCS certifications. Currently, I’m working on the Autonomous University of Madrid finishing my PhD.
I’ve worked conducting different strength tests to several high-level athletes, like the Spanish Karate Team, the Spanish Fencing Team, professional basketball players or elite track&field runners. Also, I’ve worked as a S&C in a young elite basketball team and, currently, I’m supervising the strength training of one Spanish high-level middle-distance runner.
2. You recently published an article on counter movement jump (CMJ), cortisol before and after a running race. What types of exercise cause greater neuromuscular fatigue?
Well, that’s a tricky question, since the causes of neuromuscular fatigue are not clearly known. First of all, activities with high impact on the neuromuscular system, like resistance training, are known to generate a remarkable neuromuscular fatigue. For example, a few years ago Sánchez-Medina and González-Badillo demonstrated that the decrease on velocity production on the squat exercise is highly correlated with a marker of neuromuscular fatigue like the CMJ.
However, neuromuscular fatigue has shown to occur after several different activities. For example, we have demonstrated that a middle and long distance competition produces a significant reduction on the CMJ; according to previous research that shown that a marathon run also produces neuromuscular fatigue. In fact, a recent study of us, unpublished yet, demonstrated that 1-hour fencing assault training induces a remarkable neuromuscular fatigue.
Summarizing the CMJ, as an indicator of neuromuscular fatigue, has shown to be decreased by different kinds of activities, no matter its main energy contribution or the duration of the stimulus. In fact, several authors consider the general term “fatigue” as a decrease on the ability to produce force, so every activity that produces an impairment on physical performance (run slower, throw closer, jump lower) are susceptible to lower the CMJ height.
3. What methods are possible for measuring neuromuscular fatigue?
As I said in the previous question, fatigue, ultimately, is a decrease of the ability to produce force. There are a lot of different ways to test the ability of the subject to generate force. For example, the velocity of contraction of the muscle fibers (twitch) could be used to detect impairments on the force production, as well as other sophisticated, invasive lab test. However, in the field, the best way to assess neuromuscular fatigue is through some strength-performance tests like the CMJ, the 20 meter sprint, bench press or squat velocity, etc. Personally, I would suggest the use of the CMJ since it is really easy and fast to perform almost everywhere, it doesn’t disrupt the athletes training and has shown very good relationships with other markers of fatigue on previous research.
4. What specifically did your study measure and why?
A lot is known about the lactate production or energy contribution to high-level middle and long-distance competitions, but the studies analyzing its effects on the neuromuscular performance were just a few. However, taking into account previous research, we wanted to know if the CMJ could be used to assess fatigue on high-level athletes after the most important competition of the season (the Spanish Track and Field National Championships), and how this marker of neuromuscular fatigue is related to other indicators of fatigue.
For this, we measured the salivary-free cortisol, the CMJ and the rate of perceived exertion just before and after the competition. Also, we compared the scores of the CMJ and the awakening salivary-free cortisol on the competition day in comparison with a pre-competition baseline.
5. What were the results of your study?
First, we saw a significant decrease on the CMJ and a significant increase on the cortisol after the race, and moreover, the CMJ decrease was related with the rate of perceived exertion and the post-race cortisol increase. That means that there was a significant trend for which the athletes with greater increases on the cortisol and higher perceived exertion were those with higher CMJ decreases after the competition. Also, it was interesting to found that the athletes had significantly greater awakening cortisol (+117.5%) and CMJ (+6.5%) levels the day of the competition than during a 4 weeks pre-competition baseline.
6. What were the practical implications for coaches and swimmers from your study?
Well, I think that the most important conclusion of this study is that the CMJ is a very appropriate tool to assess fatigue after an extenuate endurance event, being related to a hormonal stress marker like the salivary-free cortisol. Since the CMJ is very easy to measure on field situations with different technologies, I think that coaches could use it to assess the degree of fatigue of the swimmers not only after a competition, but, more importantly, during the training.
7. Do you think CMJ is sensitive enough to monitor fatigue after sprint competitions?
Of course I do. In fact, a college and friend of mine, Dr. Pedro Jiménez-Reyes is working a lot on this issue. For example, he has demonstrated that the decrease of speed on a sprint training session is related to the decrease of the CMJ measured after every single sprint.
Although a sprint competition involves a short stimulus (a few seconds), it could produce a remarkable degree of fatigue. Think about the following: do you think that Usain Bolt could run faster after a maximal 100-meter competition? Obviously the answer is no, because if it was yes, the sprinters would perform a maximal 100m sprint right before the competition, and that is just crazy. Thus, if some fatigue is produced affecting the ability of the athlete to produce force, it is very probable that the CMJ could detect it.
8. What are some risks of excessive training during neuromuscular and hormonal fatigue?
Again, if the fatigue is an impairment on the force production, training in that situation could lead to less efficient movements and to a lose of control and coordination of the muscles, which is known to increase the risk of injuries. Besides the risks of injuries, training with high degrees of fatigue is known to decrease physical performance in comparison with other kinds of training.
For example, it was demonstrated that performing repetitions until failure (a very common practice on resistance training) decrease the power production on some exercises, while training with the half of the repetitions that could be done increase it. Train with fatigue is equal to train producing less velocity to the movement and less power. I found the researches about training with less repetitions per set, like the cluster training method, really interesting and promising.
9. Do you think athletes train in this level of fatigue too often?
Absolutely. In fact, it is very common to hear phrases like “no pain, no gain” in the field, even in elite high performance centers that are supposed to be supervised by educated professionals.
I think that the evolution of the training methods is not to use new materials, technologies etc., but to learn to train less and more efficiently. In some specific moments, a training session could last no more than 20 minutes (for example, to produce a post-activation potentiation the day before a competition), and that is very hard to understand for some athletes and coaches.
10. What research or projects are you currently working on or should we look from you in the future?
I’m in the process of publication of two more papers about the relationships between some markers of fatigue, training load and strength on high-level middle and distance runners. Also, I’m really involved on the development of an iPhone app to measure the CMJ. We have tested the app on the laboratory with a high-tech force platform. We measured 100 CMJ with the app and with the force platform and we compared the values using some validity and reliability statistical techniques, and the results were really promising: a Pearson correlation coefficient of r=0.995 and a mean difference of 1.2cm between instruments, besides some other reliability techniques that the readers may not know. The app is called “My Jump” and will be available on June 2014. The paper about the validation of My Jump is already submitted to a top peer-review journal, so, if reviewers like it, it should be published in the near future.