Training and fitness

Insulating against injury

Running continues to be an attractive option for people looking to increase activity and fitness levels, but, unfortunately, many runners are sustaining injury in the process. Chartered physiotherapist, Mark Hynes, serves up some expert advice on how to maximise your running experience while minimising injury

Mark Hynes, 
Chartered physiotherapist, Personal Health,
Rathgar, Co. Dublin

Certain anthropologists believe that a major reason for the success of the human over the millennia is their capacity to run and that in its evolution, the homo erectus has developed physical characteristics suited to running, particularly distance running. Such characteristics include shortened arms; prominent buttocks; lengthened Achilles tendons; short and parallel toes; and a foot arch that can flex to absorb initial contact and the associated ground-reaction forces, before quickly stiffening to optimise propulsion. These ancestors ran a lot, logging hours of practice on variable surfaces, in simple, or even no footwear, functioning optimally with the anatomical tools listed above.
When the best runners from today, or from years gone by, are assessed and their technique analysed, the following traits are identified: they exhibited a high cadence, minimal vertical displacement, shortened contact time with the ground, little or no breaking phase per step and energy-efficient movements.
In the last 15-20 years, distance running has been enjoying another global wave of popularity. RunningUSA.org highlights that 19 million people finished running events in 2013 up from 4.8 million in 1990. Also, of interest is that in 1990, 75 per cent of the finishers were male, whereas in 2013, 57 per cent were female. The US Center for Disease Control reports that 22 per cent of Americans who meet the Physical Activity Guidelines do so through running.
Unfortunately, and despite all this great energy, a large percentage of runners are getting injured. In 2007, Van Gent carried out a literature review of these injuries and found evidence that between 20 per cent and 80 per cent of runners will report suffering an injury every year. Van Poppel in 2015 found that 16-33 per cent of runners finishing events had injuries during their training protocols.
Interestingly, Videbaek (2015) reported that the novice runner has a 250 per cent higher risk of injury than the experienced runner. That’s a huge difference.
What makes some runners so much more insulated against injury than others? The research says: the capacity for adaptation is a huge ally, if we use it properly.
The body will adapt, if the applied stress is not greater than its capacity to cope and strengthen. The Envelope of Function (Dye, 2005), also known as the athletes’ uninjured load capacity, is a useful concept when it comes to understanding where you are on your physical fitness trajectory and helping you generate a realistic plan for durable gains.
The concept tries to empower the athlete by getting them to spend time considering what set of physical loads are currently ‘manageable’ without injury, and at what frequency one can tolerate these loads. This simple idea can give us confidence in our starting point, or where we are currently in terms of physical capacity. From there, we can increase tissue tolerance through adaptation and strengthening, if we are consistent in our training and progress in small increments. We are trying to optimise the size of our ‘manageable envelope’ and avoid training errors that would have us operating in the ‘excessive envelope’ and risking injury. The diagram above shows that I can run for one hour with a low risk of injury, but I should not try 1.5 hours yet, as I am not trained for it. I have selected a training session that involves too great an increase in terms of load or frequency, which will increase my risk of overwhelming my tissues and causing injury.
While working as a physiotherapist in Vancouver, Canada, I attended a running workshop, which was delivered by the brilliant Irish physiotherapist Jean Lewis (Dun Laoghaire Physiotherapy and Sports Injury Clinic). She was trained by the Canadian track and field physiotherapist, Blaise Dubois (therunningclinic.com). I really like the tips give when it comes to running and progressing our capacity:

traininggraph

  • When starting a new exercise chapter, it is initially more important to be consistent than it is to progress;
  • During your training runs, especially if you are starting or restarting after a period of not running, it is a good idea to work in some walking to your running sessions. Many of the training protocols designed for people starting a new chapter of running have these walk intervals worked in;
  • Once confident and strong with your baseline level of load and training frequency, an increase in volume should not exceed 10 per cent per successful week. A successful week is a week where the athlete enjoyed each session with no pain between their runs or at the end of the week.
    The weekly long run should not exceed the longest run of the previous week by more than 10-15 minutes;
  • If you are having a big training week, boosting volume and working on cardiovascular fitness can be done by adding a cross training activity such as cycling or water-based exercise, both mechanically less stressful;
  • Be cautious and gradual when running on a new surface (hills, hard, cross-country, wet weather, slippery leaves etc.); and
    Quantify hill training by counting the number and length of your hills. Start low to ensure you are within your ‘manageable envelope’ and progress cautiously.

Training frequency
We do not know the optimal frequency at which one should train. Jean and Blaise make the interesting comment that runners tend to suffer injury to low and medium metabolism connective tissues (ie. tendon, bone, fascia), which are better-suited to less intense but repeated stresses. This raises the argument that weekly volume should be spread over as many running sessions as possible (eg. four to six sessions of running per week), rather than fewer, longer sessions. Four sessions per week may be wise, even if one to two of the runs are only 10-20 minutes. This programme of frequent running gives the body exposure to a healthy dose of mechanical stress, which drives unconscious learning of efficient mechanics and seems to be synonymous with injury-reduced running.

Physio tip

Running is an amazing form of exercise, cost-effective and often perfect for the person with a busy schedule. If you are starting out then be cautious in terms of your initial distances. Remember the goal is to have successful sessions consistently. That may have you starting at 2km per run, three times per week. This can be bulked by a five-minute power walk before and after your running, plus a 60-second walk in the middle.
If you are already running and keep hitting roadblocks when you try to progress then spend some time assessing your current pain-free capacity and ask yourself are you sticking to the principles above. If you feel you are, and you continue to have pain and dysfunction, then look up a physiotherapist in your area who has an interest in running and get yourself an assessment.
Happy running!

The whole runner

As you can imagine, with such a huge proportion of the population engaged in the activity of running, the scientific community is always trying to analyse and better understand the factors that can help insulate against injury. Here are a few interesting findings:

  • The person who starts or restarts running with good aerobic fitness and a consistent history of exercise is less likely to get hurt while running than the person who starts with poor fitness and minimal activity in the preceding window of time (Warden, 2014). If I may deduce further from this I would recommend that if someone would like to start running but is coming from a period of inactivity, it may be advisable to start with an activity that involves lower mechanical loads such as biking, use of a cross-trainer, or water jogging to help prepare their tissues and cardiovascular systems for the higher loads that come with running;       
  • Calf strength seems to be an insulating factor against injury (Clansey, 2012). I like to screen all of my leg athletes for functional dorsiflexion at the ankle joint and calf power. I believe eccentric heel drops to be a runner’s best friend when it comes to optimising symmetry of range, building power for the activity, and organising the fibres of the Achilles tendon to help avoid tendinopathy;
  • People with good overall health and nutrition are less likely to get injured running than those with poor overall health and an unbalanced dietary intake (Tenforde, 2013);
    Increased life stresses and psychosocial imbalances increase the risk of injury in runners (Moran, 2013);
  • Stress fractures decreased when soldiers slept more than 6 hours (Milgram, 2008); and
    Teenagers who sleep less than 8 hours per night are 1.7 times more likely to get injured running than those who sleep more than 8 hours per night (Milewski, 2014).

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