By Joshua Colomar (iTPA) and Mark Kovacs, PhD, CTPS, MTPS (iTPA)

The calendar of a tennis player at the junior, collegiate or professional level is increasing each year. The demands have increased with exhibition events, a more robust tournament schedule and sponsor events, which have added to an already loaded year round competitive calendar. This leads to less time for coaches to program and periodize preseason periods. While technical and tactical issues tend to be the most important aspect during players’ training, it is challenging to develop the much needed physical aspects during a shortened preseason period. We know from the research that it takes a significant number of weeks to develop strong strength and hypertrophy gains. As a result, newer techniques are developed to approach training during preseason. High Intensity Training (HIT) is a rather common technique that is being utilized more. A shock microcyle (an increased intensity of work over a short amount of time) in combination with technical/tactical work could offer enough stimulus for positive adaptation in a time efficient manner for preseason training. A recent study by Fernandez et al (2015) can offer some preliminary insights.
12 male professional tennis players (500-800 ATP Ranking) performed a 17-day HIT shock microcycle in addition to conventional tennis training. The program was formed by 3 running protocols based on the Intermittent Fitness Test (IFT) and one protocol based on on-court specific drills (‘Big X’; ‘Suicide’; ‘Recovery/Defensive’…)  Data was collected from different tests:

• 30:15 IFT
• 20m Sprint
• Countermovement Jump (CMJ)
• Repeated Sprint Ability (RSA)
• Physiological and perceptual responses (Heart Rate, RPE…)

Results indicated major increases in velocity during IFT (6.5%) and average increases in repeated sprint ability (0.5%). CMJ and 20m sprint remained statistically without significant differences.
Increases in IFT velocity didn’t correspond with increases in VO2max. Studies have demonstrated that endurance can be enhanced without changes in this parameter. These results indicate that training intervals ranging from 15s to 120s at 90-95% of HR result in specific endurance increases.

Regarding RSA improvements, specificity of training that involves similar muscles and acceleration/deceleration patterns result in positive changes in specific coordination during RSA tests.

The major concerning aspects of this type of training is the risk of overreaching/overtraining or potential injury. High intensity bouts at initial stages of season added to normal training can result in highly fatigued athletes. Further studies should be carried out to establish “how much is too much?’’ and “how much is needed to maintain gains?’’  Until then, coaches have to be very aware of load control and fatigue-related parameters like RPE, soreness, recovery quality, sleep parameters, heart rate variability measures, etc.

As coaches, we need to monitor, control and better quantify the load players are exposed to during training. HIT can be considered as a viable addition to a preseason training plan, with appropriate monitoring and understanding of the increased fatigue that is likely to occur to the athlete. Some studies revealed the validity of RPE as an effective method for quantifying load in tennis sessions. It’s the case of Gomes et al. (2015) in which RPE applied to 12 tennis players in 384 on-court tennis sessions; 23 simulated matches and 13 official matches were compared to heart rate values (internal load in this case) for the same players in the same situations. Results gave high correlation between both values and offers an easy technique that doesn’t require sophisticated equipment. This heart rate monitoring allows for relatively low cost monitoring for coaches and tennis performance specialists. Nevertheless, future investigations are needed to demonstrate validity of RPE for recovery aspects, overall season progression and fitness workouts in which specificity, volume, intensity, density and many physical parameters are involved in training.
 
To learn more about the science and practical application of physical training for tennis, please look into becoming a certified member of the International Tennis Performance Association (iTPA). www.itpa-tennis.org . Learn the latest about tennis specific training and injury prevention at the 2016 WORLD TENNIS FITNESS CONFERENCE (July 30/31st, 2016 in Atlanta, Georgia alongside the BB&T ATLANTA OPEN) www.itpa-tennis.org/tennisfitconference.html

References:
Fernández et al. Preseason Training: The Effects of a 17-Day High-Intensity Shock Microcycle in Elite Tennis Players. Journal of Sports Science and Medicine (2015) 14, 783-791.
Gomes et al. Ecological Validity of Session RPE Method for Quantifying Internal Training Load in Tennis. International Journal of Sports Science & Coaching Volume 10 · Number 4 · 2015.

By Joshua Colomar and Mark Kovacs, PhD, CTPS, MTPS

Classical descriptions present tennis as a prolonged activity (2-4 hours) of repeated, high-intensity bouts interspersed with standardized rest periods. Such description establishes that the sport is physically and physiologically demanding. However, tennis can last more than 5 hours in some extreme cases like Grand Slam and Davis Cup matches. There’s a lack of literature when quantifying such extended matches. Professional players mainly would benefit in having knowledge of fatigue development in these conditions and how it evolves during matchplay, as well as during competition weeks. To try to contextualize these doubts, Reid & Duffield (2014) offer us an interesting review on fatigue, putting together information and possible future areas of study for unanswered questions.

Professional players should be prepared for a typical situation that happens during tournament weeks and especially when playing Grand Slams. This involves scenarios of  the potential of 4-5+ hour matches and the possibility of playing 7 matches in a two week period, with only 24-49 hours of rest between each match. Fatigue occurs: the challenge for everyone is to determine the amount of fatigue and the impact it has on performance, recovery and possible injury.  It’s unclear if players experiment movement changes, poor technique or reduced cognitive performance. Fatigue responses (i.e. an athlete’s physiological profile) can be divided into changes in mechanical, contractile and cognitive characteristics:

Physiological profile:
Researchers have studied internal load parameters that are produced during tennis. This information is summarized briefly below. Most of this data is based on matches lasting 120 minutes or less:

• 60%-70% maximal heart rate.
• 60%-70% maximal oxygen consumption.
• 5mmol/L concentration of lactate.
• Elevated testosterone.
• Elevated creatine kinase.
• Reduced cortisol.
  
  

These indicators respond only to internal load in response of matchplay and not necessarily to mechanisms of fatigue or in reduced performance outcome. Nevertheless, also registrations of hypohydration and reduced glycogen availability have been recorded. This has been linked to reduced serve performance as well. To limit these negative effects, all tennis athletes should have clear strategies to limit any negative outcomes -- hydration strategies, carbohydrate ingestion and fluid replenishment.

Movement characteristics: Although literature is clear in quantity (around 8-12m per point and 600-800m per set) and duration (<10 seconds per point), movement patterns variations produced by fatigue is unclear. While it’s known that certain technical approaches have different oxygen costs it remains dubious if movement patterns change due to fatigue. Other factors may contribute as well (surface type, game style or tactical decisions). What is confirmed is that over 4 hours of prolonged matchplay and then again after 3-4 consecutive days of matchplay there is a reduction in overall movement patterns: 5% within respective days and 15% from day 1 to day 4. Whether this profile represents fatigue, or alternatively, a deliberate change in game style, isn’t clear and should be investigated in the future.

Changes in mechanical, contractile and cognitive characteristics: Studies have observed decreases in serve and groundstroke velocity during training and matches, as well as following training/matches. Despite these results, previous studies also found that the reductions in velocity were not necessarily accompanied by decrease in accuracy. This suggests that many tennis players adapt to the fatigue, by reducing the pace of the ball, but maintain accuracy. This is makes theoretical sense as it holds to the speed accuracy trade-off. In addition to these results, most of the studies were performed in simulated environments rather than in “real” competition situations. While these findings were unclear to determine if fatigue itself affects mechanical aspects like the groundstrokes, studies also indicate that velocity and accuracy can be altered during matchplay by expert players. With so many doubts, the most appropriate advice we can give and that is supported by these studies is to train for these type environments through a combination of tennis-specific strength training to allow for repeated stroke and movement mechanics over an extended period of time.

Contractile function seems to clearly reduce its function following prolonged tennis matchplay in addition to reduced neuromuscular function, particularly of the lower body, during matchplay greater than 2 hours and over consecutive days of matchplay. If this altered function precedes the reduction in movement activity profiles or relates to the accumulating physiological load remains unknown. A well-organized training program enhancing muscle resistance and function, as well as neuromuscular stimulation, should theoretically result in less reductions of these parameters.

Cognitive aspects such as perception of fatigue are also interesting in which to comment. Simulated and matchplay situations result in elevated ratings of perceived exertion, muscle joint soreness and suppressed mood states. Recent data reveals that cognitive load relates directly to physical exertion of on-court tennis training although few studies report these variables in competitive scenarios. What does seem to be clear is that there is a reduction in motivation that’s part of the fatigue process irrespective of the capacity of the muscle to contract which we’ve discussed above these lines. We can also highlight increased RPE and mental exertion to prolonged matchplay and increased error rates throughout longer or more taxing drills. This may mean that motivation and exertion are affected by the physical state, and thus alterations in stroke play and/or movement patterns. Nevertheless, motivation to perform within research settings is distinct from the motivation to perform within competitive scenarios.

Reference:
Reid, M. Duffield, R. The development of fatigue during match-play tennis. British Journal of Sports Medicine. 2014; 48:i7-i11.

By Joshua Colomar, iTPA Intern

Researchers often recommend a split step as a preparatory motion to enable quick movement for the next shot. Given that the majority of tennis strokes are hit under time pressure, it seems essential to provide the athlete with the best way to react and respond to these kind of situations. This post is focused on a 2014 research study by Nieminen and colleagues.

Nine healthy tennis players participated in a choice reaction test. The test consisted of reacting to a LED light stimulus and to move in that direction as fast as possible using the pivot step (moving out with the outside leg in the direction of the ball) as first step. Test was conducted with split step option and no split step option before the first step. Measurements taken during this test were: a) response time; b) force production time; c) total reaction time; d) horizontal and vertical mean forces; e) time to photocell. Apart from the measurements given from the choice test, other parameters were taken into account. Maximal Voluntary Contraction (MVC), Rate of Force Development (RFD), stretch-reflex and excitability of the motor neuron were registered. All these parameters would examine possible advantages of the split step over non-split step conditions and how force production capabilities, reflex sensibility and muscle activation patterns of leg muscles differ between situations.
We will divide results in two categories: time parameters and neuromuscular variables. Concerning time, in split step condition, response time, total reaction time and photocell time were significantly shorter (meaning faster) than with the no-split step condition. No differences were observed in the force production time. Observing the data available from the force plate we see that split step also produced greater vertical and horizontal peak and mean forces (more ground reaction forces). Neuromuscular variables highlighted that vertical and horizontal forces correlate negatively with the time from onset of force production to the photocell in the split step condition. Also forces correlated directly with the athlete’s RFD.

Split Step: Time registrations reveal that the split step was faster than no split step condition. This is related to timing of landing so players must be effective calculating when to execute the split step in order to make it effective. Also important is the split step technique, which includes greater forces on further foot from intended target and a pivot step to reach further and faster. Split step also developed greater forces. This may be explained by stretch reflex and elastic energy mechanisms (SSC). This study showed substantial pre-activation in some muscles before landing which is typically associated with reflex potentiation and stiffness regulation.

Non-Split Step: During this situation players leaned forward and dorsiflexed the foot, requiring greater anterior tibialis activation to enable ankle function. This preparatory movement is not as effective as the hop with split step. Although it seems a worse choice, in some occasions, split step can’t be used due to lack of time and/or improper timing. In these cases, it’s interesting that players have a well-developed strength base in anterior tibialis and vastus lateralis, muscles in charge and more involved in force production in these situations.

In conclusion, split step is faster and more effective if performed with proper timing. It generates more force due to the SSC and relies on its performance. Ankle function seems to have the greatest importance with split step. Now we can offer some practical applications based on information that we’ve been able to extract from the study review such as enhancing ankle function, strength on specific muscles, split step technique or SSC workout. When training athletes to move better it is important to work on Anterior tibialis strength, ankle range of motion to allow for more pronounced ground contacts.
 
References:
Nieminen et al. Effects of neuromuscular function and split step on reaction speed in the simulated tennis response. European Journal of Sports Science, 2014. Vol. 14, No. 4, 318-326.