It goes without saying that coaches (S&C, and otherwise) are dealing with a relatively unique challenge as we begin the process of returning to training after COVID-19. In a typical year for high performance athletes, 3-4 weeks may be near the upper end of a “transition” or active recovery period before returning to full-time training. In contrast, we are currently reaching approximately 19 weeks (as August begins) of limited or no sport-specific training. This is quite possibly the longest period that many high performance athletes have had “off” of their sport in years, or even their entire careers (we’ll ignore extended breaks post-Olympic cycle here). With this time off comes 2 things: danger and opportunity.
The opportunity in this instance, for athletes and support personnel alike, arises from the fact that high caliber athletes rarely get an extended period to heal the chronic, nagging, overuse injuries that they so often are dealing with. These injuries may not preclude the athlete from competing or training (which is why they can’t fully recover to begin with), but is certainly enough to require near-constant modification to training, reduced performance, and a lot of mental stress and frustration. There is nothing worse than being constantly preoccupied with living your life around some chronic pain, and never really feeling like you can perform at your best because of it. Herein lies the opportunity. The shutdown has allowed athletes not only an extended healing period, but also enough time to work closely with their therapists and S&C coaches (albeit virtually) within a highly controlled progression towards more fully resolving these chronic problems.
The danger(s) in this situation come from a wide variety of sources. First, while we S&C coaches have no doubt done our very best to maintain our athletes’ fitness and capacities, it is virtually guaranteed that detraining has occurred (1). This results in a greater disparity between the athletes’ physical preparedness and the typical demands of their sport. The resultant reduction in the “margin of safety” between the load and/or fatigue capacity of the athletes’ tissues and the sport-imposed demands increases the potential for both traumatic and/or overuse injuries upon re-integration (2, 3). This is one of the reasons S&C is so important to begin with: to increase this margin of safety so that the athletes can withstand the stresses they encounter in sport without breaking. In fact, Lauerson et al. (4) showed that resistance training can reduce overall injury risk by ~68%, and overuse injuries by nearly 50%. Moreover, a 10% increase in strength training volume could decrease injury risk by ~4.3% (5). However, while high-impact activities like jumping and sprinting are easily incorporated into S&C sessions, unique, sport-specific and high-velocity motions like overhead throwing are rarely replicated effectively within S&C contexts. Therefore, while continued S&C during the shutdown may have been able to mitigate the losses in general preparedness and athleticism, it may be the athletes’ re-integration into sport-specific training that represents the highest potential risk for injury.
A second and compounding danger may simply boil down to “enthusiasm”. Many athletes and sport coaches have been on the sidelines (against their will) for months now, and the desire to get back to training and/or competition may be at an all-time high. While we can appreciate the desire to get back, that very enthusiasm coupled with the aforementioned detraining effects could result in disaster if training progressions occur too quickly. This is especially the case for those athletes and coaches who feel the need to get “caught up” and try to make up for the training that was “lost” during the shutdown. Too rapid of a training progression can contribute to injury onset, even in the most ideal of circumstances (6,7). Unfortunately, now that athletes may be more deconditioned than they have been in years, this means that training demands that were previously innocuous or taken for granted may now represent significant stress, and this stress needs to be accounted for. Otherwise, the result could be a re-aggravation of that injury that they worked so hard to rehab during the shutdown, or even the creation of a novel injury that could further hamper them going forward.
A conspicuous example of these potential dangers comes from the NFL lockout of 2011. Similar to the present scenario, athletes were locked out between the dates of March 11th to July 25th, 2011, without access to team coaches, S&C or medical staff for ~15 weeks (8). As a result, the typical 14-week preseason preparatory period was largely eliminated, and the athletes had a grand total of 17 days between the end of the lockout (July 27th) and the start of preseason (August 11th) to get ready to play at 100% (8).
The results were unfortunate, to say the least. Compared to a typical year in which 1-3 Achilles tendon injuries might be expected in the 6 weeks leading into the regular season (training camp + preseason), the 2011 NFL class experienced 10 Achilles tendon injuries in the first 12 days of training camp (8). That’s a 4-fold increase in less than one third of the time. Furthermore, in the subsequent 17 days, there were another 2 Achilles injuries for a total of 12 in 29 days (8). This is compared to a total of 31 Achilles ruptures between the years of 1997 and 2002 at an average of 5 per year (8). Notably, Myer et al. (8) only examined Achilles injuries, so it would be interesting to see if the overall and overuse injury rates increased in a similar manner. It’s therefore clear that inadequate preparation coupled with overzealous training progression can potentially lead to disastrous outcomes for athletes and teams. As a result, we as S&C coaches must do our best to try to mitigate the risks that go along with our athletes’ return to performance.
The number of factors that need to be considered when attempting to plan a safe and effective return to play are endless. This is especially the case after such a long period of detraining (1). Moreover, many of these factors are interdependent, and it’s likely the effects of one will likely have corollary effects on the others. That being said, there are a number of steps we can take in efforts to mitigate the risk of injury as we begin the return to training process. While not claiming to be 100% comprehensive, the following is at least a partial list of considerations that may prove helpful to coaches as they attempt to safely navigate return to training post-COVID-19:
1.Start Slow – This may seem like a no-brainer, but every athlete and coach likely has a different interpretation of what “slow” equates to. Secondly, as alluded to above, it may be difficult for some athletes and coaches to take a step back and see the “big picture”, and not try to make up for lost time. Luckily, in efforts to combat these problems, the Australian Institute for Sport (9) published a “Best Practice Protocol” in 2015 suggesting the following calculation for safe return to play timelines:
# weeks required to return to full training = 0.5533 x (length of break in weeks) – 0.0587 x (% of full training load completed during the break) + 3.533
For this equation, the % of training should be expressed as an integer, rather than a percentage per se (i.e. 40 vs. 40% or 0.4). This guideline is useful so that all coaching and support staff may have an idea of what a reasonable timeline for return to full training looks like so that it is not grossly under- or over-estimated. Importantly, this needs to be sport and task-specific (9), as many athletes during the shutdown may be able to complete, for example, 80% of their S&C training load, but perhaps only 10% of their sport-specific load. Thus, it may be prudent to create a separate return to training timelines for each separate facet of the athletes’ training. Note: This AIS position paper has recently been updated (May 2020), and no longer presents this formula, shifting emphasis towards a more individualized, and criterion-based approach (10). However, the formula may still prove useful as a starting point.
2. Vary Intensity – Just as we would with any smart training plan, it is important to space out heavier training days to ensure adequate soft tissue recovery before pushing loading hard again. This is especially the case if those more stressful days include novel stimuli that the athletes haven’t encountered in weeks or months. Therefore, it is likely best to ensure a full 48-72 h recovery between “heavier” training sessions. Lighter work on the days between is still good, but deliberate consideration should be given to tissue recovery, especially in the initial weeks.
3. Short & Frequent – Related to the last point, for tendon health, it may be better to have shorter, and more frequent stimuli as opposed to fewer, longer sessions (11, 12). Therefore, in efforts to slowly build up the tissue resilience over the return to play process it may be better to limit the duration of training sessions so as to a) provide a more frequent stimulus, and b) indirectly limit training volumes so as to not greatly exceed the tissues’ initial capacities. This may help in creating a more efficient stimulus-recovery-adaptation cycle, as opposed to digging a large “hole” from which it is more difficult to recover from.
4. Monitor – This is a smart thing to do under all training circumstances, however, its importance is likely magnified in a return to training scenario. Not only is it important to try to quantify how much work the athlete is doing, but it is equally critical to gauge how the athletes are responding to that workload. This is especially the case when there is likely a large variability between athletes with regards to how diligently they were training during the shutdown and/or the equipment they had access to. Therefore, it may be valuable to track multiple factors including:
a) Workload – This can potentially be done with a simple sessional RPE (sRPE = minutes x RPE; 13, 14) for each training session. This will give us a daily, weekly, and eventually monthly log of time and intensity so that we can monitor and modify the Acute:Chronic Workload Ratio (below; 7). Other objective options may include volume loads, training impulses (“TRIMP”), high speed accelerations, etc. Importantly, these metrics encompass both volume and intensity, so not only may it be used for the training sessions themselves, but also potentially for specific sport-specific movements (e.g. jumps, arm swings).
b) Subjective Response to Training – This is the other half of the monitoring equation – how are athletes subjectively responding to the imposed workload? As we can pretty much guarantee that not all athletes have been equally committed to their “shutdown” training, it’s safe to say that there will be a wide spectrum of responses to a given objective training stimulus. This is especially as days and weeks of reintegration training accumulate and the athletes’ recovery abilities and practices show through. This type of monitoring may include things like general fatigue, soreness, desire to train, enjoyment of training, sleep quality and quantity, to name a few.
c) Acute:Chronic Workload Ratio (ACWR) – While by no means perfect (15), the ACWR may provide a reasonable guideline system for managing the rate at which workloads are increased (at least during normal training). Typically, we would aim to prevent the “Acute” workload (average workload over 7d) from greatly exceeding the “Chronic” workload (average workload over 28 d) by keeping the ratio between 0.8-1.3 week-to-week (7). Unfortunately, when the ratio depends on a 28 d average for a “Chronic” workload baseline, this limits the ACWR’s utility in the first few weeks of our return to training. That being said, if we maintain the guideline of an ACWR between 0.8-1.3 when planning our training, it may help anchor rates of progression more on the conservative side, and this could still prove beneficial. Alternatively, we could adhere to the classic “unwritten” 10-20% per week load increase rule (15), which would similarly anchor progressions on the conservative side. The most difficult part may then, in fact, be determining the appropriate starting intensity & volume. However, by combining the ACWR or 10-20% per week rule with the AIS’s timeline calculator (9), it is possible to work backwards from the athlete’s targeted full training load to establish a reasonable starting point.
d) High-Volume Sport-Specific Movements – One positive thing is that through continued S&C during the shutdown, athletes have still likely been able to get moderate exposure to high impact work like jumping and sprinting. However, even a comprehensive S&C program with a relatively high volume of jumping and/or sprinting may not have been enough (in isolation) to prepare the athlete fully for return to practice. This is especially the case if those practices may routinely involve 100+ jumps, in some cases more than 1x/day. As alluded to previously however, even greater danger lies with those highly-specific, high velocity movements like throwing motions, which may not be as well stimulated in S&C contexts. Therefore, it’s important to try to track these unique, high volume movements and make sure that the re-integration progresses gradually. Furthermore, just tracking volume of these movements is not enough. We need to consider the intensity levels of these movements as well because having a “pitch count” or jump count may not mean much when the intensity is not factored in. Having a similar Volume x Subjective Intensity measure like the sRPE for these movements (i.e. # efforts x Intensity of those efforts), used in a similar way to the ACWR for planning purposes may help. After all, it would be very easy for an athlete to “feel good” after 4 months off and blow past what they are prepared for in week 1 or 2. The result could be an injury they carry with them for months, or longer.
e) Soreness – We know that this is going to occur with any return to training process, however, it’s especially important to monitor common areas of overuse within the sport, and especially any areas where the athlete was dealing with an injury prior to the shutdown. While the reduced training load may have been beneficial for reducing injury symptoms in the short term, unless there was a concerted effort to rehabilitate that injury and build up work capacity in that area, there still may be underlying weaknesses that increase susceptibility to reaggravation as workloads begin to ramp up.
5. Be Predictable – When it comes to movement, if the athlete has been working hard at their S&C work throughout the shutdown, that’s great, but much of that work has likely been predictable, on a solid footing, and largely in a forward-back direction. Therefore, it is likely best for athletes to begin with what they are best prepared for, and slowly add in training elements that have become relatively unfamiliar. Naturally, this depends on the S&C program, the athletes’ adherence to that program, and the equipment/space they had access to, however, it’s likely best to start with:
a) Closed Drills – With reduced access to training partners, coaches, and/or competition, athletes likely are not prepared for a lot of reaction-based movement and/or accel/decel/change of direction at the immediate outset of training. By implementing largely closed and predictable drills, the athlete will know exactly where they are going ahead of time. This more easily lends itself to sound mechanics and footwork, hopefully reinforcing technique, and reducing the likelihood of a misstep or being caught out of position which may increase the chances of an injury.
b) Limited Lateral Movement – As much as we try sometimes, the majority of S&C work typically occurs in the sagittal plane, and therefore athletes likely haven’t been doing a ton of lateral movement work over the last 4 months. They may have been doing some lateral work, and maybe some strength work, but not likely a great deal of highly dynamic lateral work. This just needs to be kept in mind, and we need to be aware of our drill choices.
c) Gradual Velocity Increases – Similar to the above point, there has likely been limited exposure to top speed or maximum velocity movements. Therefore, a short-to-long approach with regards to linear speed work and/or judicious progression when it comes to plyometrics may be prudent in efforts to limit tissue strain opportunities due to unaccustomed velocities. This may be especially important if the athletes have been restricted in their equipment access and have been relying heavily on slower tempos or isometrics to challenge their fitness.
d) Limited Accel/Decel/Change of Direction – This follows in the same vein as the above 3 points, but when you combine unaccustomed planes, velocities, and reactions to the high impulses of the stretch-shortening cycle, it may further the likelihood of tissue injury. Again, this will depend on the type and amount of training the athlete has been performing, but it’s quite likely they have been limited in their exposure to these movements relative to what they would normally see in practice and/or competition.
e) Deliberate Sport–Specific Movements – Predictability also plays an important role in the first stages of returning to these movements. While we may have our typical go-to progressions with regards to jumping and landing (e.g. bilateral before unilateral, etc.), we also need to account for the amount of stress that sport-specific movements can place on tissues if performed in compromised ways/positions. For example, if the athlete needs to make last-minute adjustments, like an attacking volleyball player needing to adjust in the air to a poor set or mistimed jump, it may set them up in a sub-optimal position. This requires them to generate nearly all of their power through smaller, less powerful or conditioned muscles of the shoulder (rather than using their whole body). While this may never have been a consideration before, the level of detraining for these smaller muscles after 4 months may set them up for potential injury. Therefore, creating predictable and more “optimal” scenarios for the initial stages of reconditioning where the athletes can ensure appropriate technique may be a good idea.
6. Have Medical/Therapy Support – This may not be an option for all coaches, but if there was ever a time to have it, now would be that time. Injury risk is generally the highest in the initial weeks or return to play (3). This is supported by the previously discussed NFL lockout data where the vast majority of Achilles injuries occurred within the initial 2 weeks of training (8). We should therefore expect an elevation in injury rates during the initial weeks of reintegration and having appropriately trained medical support available to deal with these injuries is critical. This is especially the case if there is a coach and/or athlete group that are itching to get back to full training in week 1, and/or athletes were dealing with injuries prior to the shutdown.
7. Re-Emphasize Recovery – It’s pretty safe to say that when athletes return to practice, their bodies are going to be in the alarm phase and working 24/7 to try to rebuild and recover. As a result, the athletes are going to have to be equally, if not more, diligent about their recovery than they normally would. Stiffness, soreness, and tightness is likely going to be at an all-time high, and therefore it’s important they stay committed to their prehab/therapy, sleep, nutrition, and hydration. Recovery is one consideration that needs to be emphasized at all times, however in a situation such as return to play post-COVID-19, its importance is magnified. This could, and perhaps should be the focus of a review paper in and of itself.
8. Other Considerations – A few more things to consider as athletes return to play:
a) Ground Conditions & Footwear – This may not be as important for some athletes as it is to others. After all, if athletes train, play, and live all in the same shoes or on the same footing, the issue may be irrelevant (e.g., court sports). However, it the athletes’ field of play is on sand (e.g., beach volleyball) or requires cleats (e.g., soccer, rugby, or track), it’s likely something that needs to be considered. After all, it may take some time for the muscles in the feet and ankles to adjust to the unstable footing and/or the increased forces that occur when accelerating, decelerating and changing directions at high speeds with unfamiliar footwear. Depending on the circumstances, it may be best to either limit the re-exposure time to multiple shorter sessions throughout the week, or give recovery days between sessions where athletes can still train, but do so off-sand or out of cleats just to alleviate the stress on the smaller bones and tissues that act as the athletes’ foundation. This may be a relatively minor detail, but it is certainly worth consideration.
b) Hot Environment – While the majority of heat acclimation can occur rapidly over the course of several days, full acclimation may take 14 days or longer (16). During this time, if the athlete is training in the heat, they will be under much more physical strain due to their body’s inability to cool efficiently, especially if they’ve been living their quarantined lives in perpetual air conditioning. As a result, coaches need to be aware of the symptoms and treatments associated with exertional heat illnesses (EHI) and have a plan in place to deal with these issues. Most problems occur within the first 5-6 days of heat exposure, but athletes may be susceptible for 14+ days, especially if they are larger, have excess body fat, wear a lot of equipment, or are deconditioned (17). As a result, it may be wise in the first few weeks of training to take steps to avoid excess heat accumulation. Some possible solutions may include running initial practices with reduced equipment, taking more frequent breaks to cool down/hydrate, and cutting conditioning volumes back significantly (17) during this initial acclimation period. While it may seem like an unlikely problem to have, it is worth noting that exertional heat stroke (the most extreme of EHI) has been reported to be the third highest cause of sports-related fatality in high school and college sports (17). Therefore, we must be cognizant of it, and be prepared to deal with it. Be vigilant if training outdoors with a wet bulb globe temperature in excess of 27.8°C, and be prepared to cool athletes rapidly if they start to show symptoms. The 30 mins immediately following symptom presentation is critical. Cold water immersion is the best method to get core temperature down rapidly (17).
In summary, while by no means being an exhaustive list of all programming factors affecting return to play post-COVID-19, I hope that this article may provide some insights for S&Cs, sport coaches, and/or athletes as they initiate their journey back to full-capacity training. While we can never eliminate injury risk entirely, I hope to have highlighted at least some mitigating factors that may not have been under consideration before, thereby contributing to an overall better and healthier return to play. For more information regarding return to play guidelines, see (10, 17).
- Start Slow, and try to keep the long-term, big picture in mind
- Vary Intensity, and try to make sure the soft tissue gets the rest it needs before pushing it hard again
- Short & frequent sessions may help with this purpose of making sure tendons don’t get overextended, and may help optimize collagen remodelling
- Monitor what your athletes are doing, both objectively and subjectively
- Be predictable and gradual in your programming
- Have medical/therapy support
- Re-emphasize recovery efforts: prehab/therapy, sleep, nutrition, and hydration
- Be aware of environmental factors that can compound injury risks during return to play
Andrew Cochran, PhD, CSCS. Andrew completed his PhD in exercise physiology with a specialization in sport nutrition at McMaster University in 2013. He has since been employed at the Canadian Sport Institute Ontario coaching Olympic, Paralympic, and development-level athletes as both a Sport Physiologist (2013 – 2015) and Strength & Conditioning Coach (2015 – Present). He currently serves on the National Supplement Advisory Group to Own the Podium and the Canadian Olympic and Paralympic Sport Institute (COPSI) Network, and has been a member of the CSCA’s Advisory Team since its inception. He currently works with the sports of Beach Volleyball, Diving, and Wheelchair Rugby.
- Mujika, I., Padilla, S. Detraining: Loss of training-induced physiological and performance adaptations. Part II: Long-term insufficient training stimulus. Sports Med 2000; 30: 145-154.
- McGill, S. The biomechanics of low back injury: implications on current practice in industry and the clinic. J Biomech 1997; 30: 465-475.
- Stares, J.J., Dawson, B., Peeling, P., Heasman, J., Rogalski, B., Fahey-Gilmour, J., Dupont, G., Drew, M.K., Welvaert, M., Toohey, L. Subsequent injury risk is elevated above baseline after return to play: A 5-yr prospective study in elite Australian football. Am J Sports Med 2019; 47: 2225-2231.
- Lauersen, J.B., Bertelsen, D.M., Andersen, L.B. The effectiveness of exercise interventions to prevent sports injuries: a systematic review and meta-analysis of randomized controlled trials. Br J Sports Med 2014; 48: 871-877.
- Lauersen, J.B., Andersen, T.E., Andersen, L.B. Strength training as a superior, dose-dependent and safe prevention of acute and overuse sports injuries: a systematic review, qualitative analysis, and meta-analysis. Br J Sports Med 2018; 52: 1557-1563.
- Blanch, P. Gabbett, T.J. Has the athlete trained enough to return to play safely? The acute:chronic workload ratio permits clinicians to quantify a player’s risk of subsequent injury. Br J Sports Med 2016; 50: 471-475.
- Gabbett, T.J., Hulin, B.T., Blanch, P. Whiteley, R. High training workloads alone do not cause sports injuries: how you get there is the real issue. Br J Sports Med 2016; 50: 444-445.
- Myer, G.D., Faigenbaum, A.D., Cherny, C.E., Heidt Jr., R.S., Hewett, T.E. Did the NFL lockout expose the Achilles heel of competitive sports? J Orthop Sports Phys Ther 2011; 41: 702-705.
- Australian Institute of Sport. (2015). Prescription of training load in relation to loading and unloading phases of training (1st Ed.) Australian Institute of Sport. Bruce, ACT, Australia, Australian Sports Commission.
- Australian Institute of Sport. (2020). Prescription of training load in relation to loading and unloading phases of training (2nd Ed.) Australian Institute of Sport. Bruce, ACT, Australia, Australian Sports Commission.
- Paxton, J.Z., Hagerty, P., Andrick, J.J., Baar, K. Optimizing an intermittent stretch paradigm using ERK1/2 phosphorylation results in increased collagen synthesis in engineered ligaments. Tissue Eng Part A 2012; 18: 277-284.
- Baar, K. Stress relaxation and targeted nutrition to treat patellar tendinopathy. IJSNEM 2019; 29: 453-457.
- Foster, C., Florhaug, J.A., Franklin, J., Gottschall, L., Hrovatin, L.A., Parker, S. et al. A new approach to monitoring exercise training. J Strength Cond Res. 2001; 15: 109-115.
- Haddad, M., Stylianides, G., Djaoui, L., Dellal, A., Chamari, K. Session-RPE method for training load monitoring: Validity, ecological usefulness, and influencing factors. Front Neurosci 2017; 11: 612.
- Wang, C., Vargas, J.T., Stokes, T., Steele, R., Shrier, I. Analyzing activity and injury: Lessons learned from the acute:chronic workload ratio. Sports Med 2020; 50: 1243-1254.
- Periard, J.D., Racinais, S., Sawka, M.N. Adaptations and mechanisms of human heat acclimation: Applications for competitive athletes and sports. Scand J Med Sci Sports 2015; 25 (Suppl 1): 20-38.
- Caterisano, A., Decker, D., Snyder, B., Feigenbaum, M., Glass, R., House, P., Sharp, C., Waller, M., Witherspoon, Z. CSCCa and NSCA joint consensus guidelines for transition periods: Safe return to play following inactivity. Strength Cond J 2019; 41: 1-23.