Physiotherapy

The University of Plymouth Physiotherapy students are available pre and post race to undertake sports massages and to provide tips and advice.

Podiatry

Runners can visit the podiatry team at the University of Plymouth minor foot injuries clinic in the runners' village 2011 Plymouth Half Marathon. See below for excellent Podiatric advice...

Foot blisters: podiatric advice for the 2011 Plymouth Half Marathon
Emma Cowley MSc 

Lecturer in musculoskeletal podiatry
University of Plymouth

www.runnersmedicalresource.com

Friction blisters of the skin are one of the most common running injuries (Caselli and Longobardi, 1997).  They are often painful lesions and occur where the epidermis of the skin (the surface) has mechanically separated from the dermis (the living part) due to overlying friction (figure 1) - the gap fills with a plasma-like fluid creating an intact blister (Knapik et al., 1995). The factors that predispose the skin to blistering include the extent of friction force and the number of repetitions of that force (Knapik et al. 1995).  Some people may be more prone to friction blisters of the feet than others with risk factors including:

 

Tips to reduce the risk of blistering:

Keep your feet as dry as possible
Knapik et al. (1995) reported that dry skin has a lower co-efficient of friction than ‘moist’ skin.  So the aim is to keep the skin of the feet as dry as possible during a prolonged run.  It is not recommended that anti-persperant with  moisturisers be used for this, since research suggests that this method, as well as the use of drying powders such as talc, does not reduce the incidence of blisters on the feet (Reynolds et al., 1995).  A study by (Knapik et al, 1998) showed that a deodorant without moisturiser may be effective in reducing foot blisters during hiking but the risk of skin irritation cannot be ignored and hence this is still not clinically advisable.  Perhaps the best way to achieve dry skin is by good footwear design – using breathable shoe upper materials or designs that include vents – or to ‘wick’ the moisture away from the skin with socks made of specialist ‘wicking’ fibres.  The careful repeated application on surgical spirit with a cotton bud – separating the toes after allowing it to dry off – can act as an astringent to sweat glands reducing the amount of sweat produced.  Anecdotally this is recommended although research had not been conducted to support this method.

Training your running shoes
With good advice from specialist podiatrists and running shops you will hopefully have found a design of trainer that is a good design for you to run in.  The key to your shoes working for you, however, is preparing you and your shoes for the race.  New trainers will be rather unforgiving since the glues firmly adhering the materials of the sole together will be un-fatigued, the leather may be catching on bony prominences and the laces will be slippery (if nylon).  Your shoe needs to work with your foot and as you wear it the shoe yields during training miles, until it is ready for the race.  Similarly overused shoes will be too fatigued which could lead to movement of the foot in the shoe.  The skin of the foot must become accustomed to the pressure and shear points inside the shoe and develop protective calluses where needed during training.  A study by Patterson et al. (1994) found that army recruits who wore their boots for less than twenty hours prior to a prolonged hike significantly elevated their risk of blistering.  As a guide you may wish to convert this into a rule of thumb: wear your trainers for 100 miles before racing in them.

Good lacing techniques
Whilst evidence is not overly abundant in this field a study by Hagen and Hennig (2009) found that the best way to reduce shear-creating movements of the foot in trainers is to lace firmly and high up the shoe, using the top eyelets to secure the laces and prevent slippage (figure 2). 

Wear acrylic socks
A study by Herring and Richie (1990) indicated that acrylic fibre socks reduced the incidence and size of blisters in long distance runners.  This theory was enforced with a finite element analysis study by Dai et al. (2005) who found that reducing the co-efficient of friction of socks reduced the likelihood of blistering.

Treat problematic flat feet
Whilst flat feet (pes planus) are not always problematic or even symptomatic a study by Knapik et al. (1999) found that pes planus was a risk factor for blistering.  A typical such blister may appear under the arch as shown in figure 3.

By consulting a podiatrist the movements and function of a flat foot that may lead to this type of blister can be addressed with foot orthoses and advice on footwear etc.

If all this fails…
If prevention has not been successful and a blister entails effective management is essential to avoid pain and infection of the surrounding tissues (cellulitis) (Brennan, 2002).

Firstly, pain can be reduced in most cases by removing the friction.  Mid-race this does not mean removing your shoes!  Instead use of sterile hydro-colloid gel dressings (available at all good chemists and drug stores e.g. Compeed™) can help.  It is of absolute importance, however, that these dressings are only applied to clean skin.  After the race it might be best to remove the original dressing which may ‘ruck up’ during the remainder of the race, clean the skin properly, dry it and then apply a fresh dressing.  If the blister has ‘burst’ releasing its fluid, a portal for infection is left open and the remaining flap of loose skin could even help harbour infection.  In the event of a blister ‘de-roofing’ or bursting (lysing) you should seek podiatric care to remove the flap of skin and dress the wound using a clean technique and sterile dressings or skin glues (Levy et al. 2006).  Note that tearing the skin flap yourself is likely to result in a bleeding and painful exacerbation of your blister which is not desirable!

Intact blisters that are not excessively painful can be shielded using adhesive chiropody / podiatry felt shaped like the illustration in figure 4 and not dressed unless further open wounds are present. 

You should not intentionally burst an intact blister since this increases the likelihood of infection and you lose the protective ‘bubble’ of fluid.  An intact blister is sterile inside.

Summary:
Prevention is

• better than cure
• Dress a burst blister using sterile dressings on clean skin and remove further friction
• Don’t intentionally burst blisters – risk of infection!
• Seek podiatric care where necessary to remove flaps of skin
• Seek medical assistance if any signs of infection (redness, bad smell, pus, swelling) become apparent at the site of a blister

 

Runners can visit the podiatry team at the
University of Plymouth minor foot injuries clinic
in the runners’ village
2010 Plymouth Half Marathon 

 

References
1. Brennan, F H (2002) Managing blisters in competitive athletes, Curr Sports Med Rep. 1(6):319-22

2. Caselli, M A and Longobardi S J (1997) Lower extremity injuries at the New York City Marathon, J Am Podiatr Med Assoc;87(1):34-7

3. Dai, X Q, Li, Y, Zhang, M, Cheung J T M, (2005)  Effect of sock on biomechanical responses of foot during walking, Clinical Biomechanics, 21:314–321

4. Hagen, M and Hennig, E M, (2009) Effects of different shoe-lacing patterns on the biomechanics of running shoes, Journal of Sports Sciences, 27(3): 267–275

5. Herring, K M and Richie, D H (1990) Friction blisters and sock fiber composition. A double-blind study, J Am Podiatr Med Assoc., 80(2):63-71.

6. Knapik, J J, Reynolds, K L, Duplantis, K L and Jones, B H (1995) Friction blisters. Pathophysiology, prevention and treatment, Sports Med. 20(3):136-47

7. Knapik, J J, Reynolds, K and Barson, J (1998) Influence of an antiperspirant on foot blister incidence during cross-country hiking, J Am Acad Dermatol,  39:202-6

8. Knapik, J J, Reynolds, K and Barson, J (1999) Risk factors for foot blisters during road marching: tobacco use, ethnicity, foot type, previous illness, and other factors.
Mil Med. 164(2):92-7

9. Levine, N (2009) Recurrent, pruritic blisters on lower extremities: consider conditions that produce vesicles, Geriatrics, 64 (1): 24

10. Levy P D, Hile, D C, Hile, L M and Miller, M A (2006) A prospective analysis of the treatment of friction blisters with 2-octylcyanoacrylate, J Am Podiatr Med Assoc., 96(3):232-7

11. Patterson, H S, Wooley, T W and Lednar, W M (1994) Foot blister risk factors in an ROTC summer camp population, Mil Med., 159(2):130-5.

12. Pollack, A and Scheinberg, S (2006) A New Technology for Reducing Shear and Friction Forces on the Skin: Implications for Blister Care in the Wilderness Setting, Wilderness & Environmental Medicine, 17(2):109-119

13. Reynolds, K, Dan, A, Roberts, D, Knapik, J, Pollard, J, Duplantis, K and Jones, B (1995) Effects of an antiperspirant with emollients on foot-sweat accumulation and blister formation while walking in the heat, J Am Acad Dematol., 33:626-30