The Right Workload to Avoid Injury

How do training and competition workloads relate to injury? This question was recently addressed in several articles published in the British Journal of Sports Medicine.

Workload is the total amount of stress applied over time. When an athlete trains or competes, they are exposed to various workloads. The nature of the workload and characteristics of the athlete (predisposition) together determine an individual’s susceptibility for injury during any given training session or competition.

Take Aways

  • The ideal training workload maximizes improvements in fitness and minimizes fatigue, illness, injury, and overtraining.
  • Too much or too little stress can increase the risk for injury. Sudden spikes in workload also increase risk for injury.
  • Identical external training loads can have different effects on two individual athletes.
  • Assess an athlete’s workload prior to implementing a training programme to ensure there is not a spike in workload (greater than 10%). Continue to monitor the individual effects of external workloads through athlete check-ins.

The Predisposed Athlete

Multiple factors may predispose an athlete to injury, such as:

  1. Previous injury
    1. A previous injury (especially if incompletely rehabilitated) increases your risk for another injury. Makes sense, right? Previous injury increases risk due to weakened structures, and through compensation — for instance, loading your left leg more to avoid weight on your  injured right leg.
  2. Modifiable factors
    1. Aerobic power: your ability to transfer oxygen from the environment to working muscles.
    2. Muscular strength: the ability of your muscles to produce force.
    3. Neuromuscular control: your ability to move well in a variety of challenging and novel environments — assessed by Chiropractors, and other healthcare professionals.
      1. To move, signals from your brain are sent to your muscles via nerves.
      2. Your brain also keeps a copy of the expected sensory experience, and compares actual movement to expected movement. Did you move the way you intended?
      3. Joints, muscles, skin, fascia, and other structures send information to the brain about actual movement.
      4. If the nervous system or any of the structures above are functioning sub-optimally, your ability to move well decreases.
    4. Tissue resilience: your tissue’s (ligaments, tendons, etc.) ability to resist being stretched, compressed, bent, or otherwise.
    5. Nutritional status: the quality of your diet, and the level of key nutrients obtained from food and maintained in the body to support important metabolic processes; such as those processes that optimize power, strength, and resilience.
    6. Psychosocial factors: your ability to cope with the demands of exercise, to manage stress, and to respond to social stimuli or pressures. Check out this prior post on wellness in athletic training.
    7. Other: sleep quality, toxin exposure, immune status, etc.
  3. Non-modifiable factors
    1. Genetics
      1. Arguably modifiable through epigenetic processes — changes in DNA function (replication and protein synthesis) without changing the DNA sequence.
    2. Age
    3. Sex
    4. Anatomy

The Susceptible Athlete

Increasing workload (the total amount of stress placed on an individual over time through training and competition) results in both increased fitness and fatigue, and either positive adaptation or injury (negative adaptation). Three factors are commonly manipulated to alter training workloads — frequency, intensity, and duration. Remember that a key principle of training is individuality — athletes respond to external loads differently based how characteristics of the external workload interact with their individual biomechanics and physiology (their predisposition).

Athletes who are exposed to sudden or chronically high external stress are susceptible to injury. These kinds of workloads decrease an individuals ability to adapt, and overwhelm their capacity for improvements in modifiable risk factors — tissue resilience, neuromuscular control, etc. Interestingly, chronically low workloads can also increase risk of injury… not enough stress for adaptation, or the stress does not resemble competition stresses.

  1. Fitness & Fatigueimg_1353
    1. As workload is increased, so does fitness; the harder you train, the stronger you are.
    2. But, you may also notice that the harder you train, the more recovery you need. Elite athletes who train 3 times per day reach high levels of fitness, but they also experience high levels of fatigue.
    3. An old rowing coach explained it like this — as you train, fitness increases, but so does fatigue. Rest results in reductions in fitness and fatigue; but, fatigue decreases at a faster rate. So, training makes you strong, and rest makes you fast! This explains (in part) the idea of periodization or the idea of tapering before a race where the goal is to maintain fitness but lessen fatigue. See the graph.
  2. Adaptation
    1. For change to occur, good or bad, the system needs to be stressed.
    2. At the cellular level, adaptation may result in atrophy (smaller cells), hypertrophy (bigger cells), hyperplasia (more cells),  or metaplasia (swapping cell types).
    3. The body is good at progressively adapting to workloads that are slowly increased.
    4. To avoid injury and promote positive adaptation, workloads should be increased no more than 10% per week.
  3. Injury
    1. When workloads, training environments, or rules of the game challenge the system in a way that does not allow adaptation, injury may result.
    2. Sudden increases in workloads increase injury risk… such as that 20k run after taking it easy for 6 months.
    3. Chronically low workloads can also increase risk for injury. Low workloads don’t stress the system enough for beneficial changes in fitness or for preparedness in competitions.

Finding the Right Workload

Considering all of the above, how do you find the right workload?

  1. Talk to experts. Find a personal trainer or coach who you trust who can help you modify the frequency, intensity, and duration of your training sessions to prepare you for competition. Engage health care practitioners in conversation regarding previous injuries and modifiable risk factors.
  2. Understand that workload is the interaction of your unique physiology with the external environment. Everyone responds differently to the same environmental stimulus.
  3. Physiological markers such as heart rate variability or heart rate recovery and psychological markers such as the POMS questionnaire may be used to monitor workload.
    1. Remember theses symptoms of overtraining (more in a prior post)? persistent or worsening fatigue, irritability, depression, loss of weight, recurrent infections, salt cravings, sugar cravings, and reduced performance despite adequate rest.
  4. An athlete’s well-being should be monitored with questions relating to mood, stress levels, energy, sleep, diet, and soreness in commonly injured areas for their given sport.

Resources

Drew, M., Cook, J., & Finch, C. (2016). Sports-related workload and injury risk: simply knowing the risks will not prevent injuries: narrative review. Br J Sports Med., 50, 1306-1308

Gabett, T. (2016). The training-injury prevention paradox: should athletes be training smarter and harder? Br J Sports Med, 16(50), 273-280 (Full Text)

Windt, J. & Gabbett, T. (2016). The workload-injury aetiology model. Br J Sports Med., Online First. (Great Info-graphic in this link)