user error

‘A user error is an error made by the human user of a complex system.’



The life-span and productivity of a precision-engineered tool like the human body is directly related to the skill level of the operator and their knowledge of it’s ‘modus operandi’ and maintenance needs. Certain engineering principles are universal and timeless but it is important to read the ‘small print’ regarding each manufacturers definition of a ‘lifetime guarantee’ and ‘normal wear and tear’ as these definitions vary greatly between countries, cultures and institutions.


The Bulletproof Runner workshop has been designed as an applied, ‘hands on’ education in the skillful operation of the running anatomy by improving technique (biomechanics) and enhancing biological adaptation and recovery (bioenergetics).

Click HERE to find a local Bulletproof Runner workshop (more regions coming soon)


Run in the sun

“Let there be light”

Genesis 1:3

The use of Heliotherapy or ‘sun-bathing’ for health reasons precedes recorded history, but the first documents recording the theory and practice of ‘solar therapy’ were written by the ancient Greeks. Heliopolis, the ancient Greek city of the sun was famous for it’s healing temples. Hippocrates (the father of modern medicine) had a large solarium within his sanatorium on the island of Cos. The famous physician/historian Herodotus who believed that ‘the sun feeds the muscles’ recounts a visit to a site of a historical battle between the ancient Egyptians and Persians in his book ‘the histories’:

“The heads of the Persians are so weak that, if you were to toss a single pebble at one, you would make a hole in it. But the heads of the Egyptians are so strong that, using a stone, you could break one open only with a good deal of effort. They said that the reason for this (which I found easy to believe) was that the Egyptians, beginning straightaway in childhood, shave their heads and expose them to the sun, which hardens the bone. This is also the reason why Egyptians do not go bald: among the Egyptians one may observe the fewest balding men of any race in the world. This, then, is the reason that the Egyptians have such strong heads. The Persians have such weak heads for this reason: they are always wearing felt caps from the beginning of their lives.”

From the late 1800s, heliotherapy became a key part of certain treatment regimes for tuberculosis, rickets and war wounds, reaching a peak in the 1920s-30s with the ‘Rollier method’ of heliotherapy becoming a standard procedure in certain hospitals in Europe and the US (fig 1).


Although heliotherapy has been usurped by the modern sciences of ‘photobiology’ and ‘photomedicine’, and our understanding of solar radiation and it’s effects on the human body has evolved (fig 2 and fig 3), evidence suggests that intelligent use of sunlight is (still) a powerful tool in preventing many acute and chronic medical conditions.


BTR-light-therapy-fig3BTR believe that running in the early morning sun is a natural way to maintain metabolic health, accelerate recovery and avoid Over Training Syndrome (OTS).


Hobday RA (1997) Sunlight Therapy and Solar Architecture Medical History

Herodotus The Histories Penguin Books

Cannell JJ et al (2008) Athletic Performance and Vitamin D Medicine & Science in Sports and Exercise

Cannell JJ et al (2008) Treatment of Vitamin D deficiency Expert Opin. Pharmacother

Karu TI (2010) Multiple roles of cytochrome c oxidase in mammalian cells under action of red and IR-A radiation IUBMB LIFE

Holick MF (2004) Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers and cardiovasular disease Am J Clin Nutr

Lindqvist PG et al (2016) Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort Journal of Internal Medicine

Begum R et al (2015) Near-infared light increases ATP, extends lifespan and improves mobility in aged Drosophila melanogaster. Biol. Lett. rsbl

Wired to Run (the runners high)

“We all need something to help us unwind at the end of the day. You might have a glass of wine, or a joint, or a big delicious blob of heroin to silence your silly brainbox of its witterings but there has to be some form of punctuation, or life just seems utterly relentless”

Russell Brand

A running-induced altered state of consciousness is known as the ‘runner’s high’. The ‘runner’s high’ has been described subjectively as pure happiness, elation, a feeling of unity with one’s self and/or nature, endless peacefulness, inner harmony, boundless energy, and a reduction in pain sensation. It would appear that there is an intrinsic, neurobiological reward for humans who run long distances, that might explain why humans run for ‘pleasure’, despite the increased metabolic cost and risk of injury. An emerging theory in the sports medicine and evolutionary biology literature is that endurance exercise elevates endocannabinoids (produced internally), eliciting the same ‘psychoactive’ effects experienced from exogenous (ingested) cannabinoids such as marijuana. Cannabis and cannabinoid-based medications have been used for centuries to treat pain, spasms, asthma, sleep disorders, depression and loss of appetite. More recently (the last 30 years), their antispastic, analgesic, neuroprotective and anti-inflammatory properties have been confirmed in over 100 clinical trials. The anticipation of the endocannabinoid ‘high’ experienced after a long run is instrumental in establishing a long-term running habit (fig 1). Some researchers consider this an ‘addiction’, with potentially negative consequences to family life and work commitments if an ‘addicted’, habitual runner is prevented from running (due to injury, weather, travel etc,) and begins to suffer from ‘withdrawal symptoms’. These symptoms (irritability, restlessness, frustration, depression, insomnia and general fatigue) are remarkably similar to the ‘symptoms’ experienced by people prevented from eating and sleeping. Should these species-specific, health-promoting activities also be classified as ‘addictions’ with potentially-negative-withdrawal symptoms? If homo sapiens did evolve as endurance walking, running, hunter gatherers, then low-intensity-long-duration movement is probably a species-specific requirement for optimal-metabolic and psychological health. However, not all species are ‘wired to run’, and many non-cursorial animals such as rats, ferrets and bodybuilders experience a negative-biochemical reaction to endurance exercise (fig 2), and must seek alternative strategies to meet their cannabinoid needs (fig 3).






Dietrich A, McDaniel WF (2004). Endocannabinoids and Exercise. Br J Sports Med

GrotenhermenF, Muller-Vahl K (2012) The therapeutic potential of cannabis and cannabinoids. Dtsch Arztebl Int

Duhigg C (2012) The Power of Habit

Glasser W (1976). Positive Addiction

Robbins JM, Joseph P (1985) Experiencing Exercise Withdrawal: Possible Consequences of Therapeutic and Mastery Running. Journal of Sports Psychology

Raichlen DA et al (2012) Wired to Run: exercise induced endocannabinoid signalling in humans and cursorial mammals with implications for the ‘runner’s high’. J Exp Biol

Zombie breathing patterns

“Over the oxygen supply of the body, carbon dioxide spreads its protective wings.”

Johannes Friedrich Miescher, MD, 1885

Most cursorial animals rely on ‘panting’ to thermoregulate during exercise, but humans have adopted a more efficient ‘sweating strategy’. This physiological adaptation underpins the phenomenon of the ‘persistence hunt’ and the ‘endurance-running hypothesis’. Exaggerated breathing behaviour known as ‘hyperventilation’ or ‘overbreathing’ (fig 1) is a sign of physiological stress and a classic symptom of Over Training Syndrome (OTS). All aspects of OTS have biological, psychological and social influences that need to be considered, but the act of ‘breathing’ is a biomechanical behaviour that can be COACHED.


Maintaining adequate oxygen delivery to the cells is essential to human health, particularly for the brain, which requires consistent delivery of both glucose and oxygen to function properly (see zombie runners post). Numerous physiological systems are involved in supporting oxygen homeostasis, but one of the most crucial (and the most misunderstood) is the level of carbon dioxide (CO2) produced by oxidative activity of the cells (fig 2) and maintained in extra-cellular fluid and blood. The amount of CO2 in solution in the blood (carbonic acid) influences the acidity (pH) of the blood; the pH and temperature of the blood in turn affects the affinity of haemoglobin for oxygen and it’s ability to release oxygen to tissues and cells (dissociation) (fig 3). Hyperventilating or ‘overbreathing’ reduces carbonic acid in the blood, creating a higher pH (alkalinity), increasing the affinity of haemoglobin for oxygen and reducing it’s ability to dissociate and release oxygen to the cells.




High pH increases the affinity of haemoglobin for oxygen and reduces dissociation (release to tissues)

Low temperatures have the same effect (see zombie diet post)

Hyperventilation in otherwise healthy runners is symptomatic of metabolic acidosis from prolonged fasting or low-carbohydrate dieting, OR a habitual-faulty breathing pattern due to chronic stress (sympathetic dominance) and poor biomechanics (fig 4).


BTR considers the ‘skill’ of breathing to be as important as the skill of running and is a fundamental part of the ‘Bulletproof Runner’ system.


Bramble DM & Lieberman DE (2004) Endurance running and the evolution of Homo. NATURE

Langdon JH (2005) The Human Strategy: An Evolutionary perspective on Human Anatomy

Ganong WF (2005) Review of Medical Physiology

Gamble JL (1960) Chemical Anatomy, Physiology and Pathology of Extracellular Fluid

Stewart PA (2009) Stewart’s Textbook of Acid-Base

Henderson Y (1938) Adventures in Respiration

Heppenstall ME (1944) The relation between the effects of the blood sugar levels and hyperventilation on the electroencephalogram J Neurol Neurosurg Psychiatry

Buteyko K. (1990). The Buteyko Method, An Experience of Use in Medicine

The Zombie Workout


The biggest risk factors for development of Over Training Syndrome (OTS) in runners are inappropriate training volumes, and intensities that compromise mitochondrial function (fig 1) and storage and utilisation of liver and muscle glycogen (the hallmark of the BTR zombie runner)  (fig 2 ). The risk of OTS is further increased when inappropriate training is combined with a zombie diet, or any diet that promotes excessive proteolysis/gluconeogenesis and autoxidation of lipoproteins (high dietary PUFA intake or reliance on ‘burning’ stored-body-fat PUFAs). The adaptive benefit of any type of exercise or training is based on the synthesis of new proteins (especially enzymes). Mitochondrial protein biogenesis and enzyme function in particular are paramount for healthy, high-performance running.



Runners motivated by purely ‘health’ reasons should avoid the ‘anaerobic glycolysis’ zone as much as possible. Runners motivated to improve their ‘performance’ should design their excursions into this zone based on their age and specific event.

At BTR we recommend ‘dipping into the well’ no more than every 72hrs as a general rule of thumb.


Selye H (1978) The Stress of Life

Verkhoshansky Y (2007) The Block Training System in Endurance running

Verkhoshansky N (2012) General Adaptation Syndrome and it’s application in Sport Training

Frayn KN (1996) Metabolic Regulation: A Human Perspective

Atkinson DE (1977) Cellular Energy Metabolism and It’s regulation

Meerson FZ (1984) Adaptation, Stress, and Prophylaxis

Viru A (2008) Adaptation in Sports Training

The Zombie Diet


Torpor is a state of decreased physiological activity in an animal, usually by a reduced body temperature and metabolic rate. Torpor enables animals to survive periods of reduced food availability. A torpor bout can refer to the period of time a hibernator spends at low body temperature, lasting days to weeks, or it can refer to a period of low body temperature and metabolism lasting less than 24 hours, as in “daily torpor”.

From Wikipedia, the free encyclopedia

Human beings are homeotherms. Maintaining a consistent body temperature of between 36 to 38 degrees is a homeostatic requirement for optimal enzyme function and metabolic health (fig 1). Poikilotherms will have four to ten enzyme systems that operate at different temperatures but because their metabolism is variable and generally below that of homeothermic animals, maintaining a large brain is generally beyond poikilotherm animals. The metabolism of poikilotherms favors strategies such as ambush hunting rather than stalking-sprinting or persistence-endurance type hunting with it’s high movement cost. As they do not use their metabolisms to heat or cool themselves, total energy requirement over time is low and for the same body weight, poikilotherms need only 5 to 10% of the energy of homeotherms.



A consistently low-morning-body temperature is associated with ageing and chronic stress and is a symptom of overtraining syndrome (OTS) in endurance athletes (fig 2).


Aside from unintelligent training behaviour (see BTR training zones), the biggest influence on ‘homeothermic ability’ is eating behaviour and nutrition. The low–carbohydrate diets and ‘intermittent fasts’ that are gaining popularity amongst the ‘barefoot running’ and ‘natural movement’ communities create stressful levels of gluconeogenesis that reduce the liver’s ability to convert circulating levels of inactive-thyroid hormone (T4) to the active form (T3). The amount of circulating T3 in the body is the biggest influence on cellular metabolism and heat production (thermogenesis). The low levels produced by the liver during fasting and low-carbohydrate dieting are responsible for the reduced Basal Metabolic Rate (BMR) observed in each phase of yo-yo dieting.

A low-carbohydrate diet invariably implies a high fat intake and/or high protein intake which, in western society, invariably implies a high PUFA (polyunsaturated fat) intake (fig 3) due to modern-industrialised-agricultural methods. The ‘essentiality’ of PUFAS (both omega 6 and omega 3) is open to debate but the physico-chemical realities of the autoxidation rates and free radical production of highly unsaturated oils at mammalian body temperatures is not (fig 4).



When the metabolic ‘insult’ of excessive lipoprotein oxidation (rancidity) due to high PUFA intake is added to the metabolic ‘injury’ of excessive gluconeogenesis created by low-carb dieting and fasting, the normally-stable homeothermic ability of mammalian physiology becomes unstable, and body temperatures can drop dramatically in response to environmental temperatures, leading to torpor and hibernation (fig 5).



BTR Considers the combination of low-carbohydrate intake, intermittent fasting and high PUFA intake is the perfect diet plan for Zombies (fig 6).



Barnes BO, Galton L (1976)  Hypo-thyroidism: The Unsuspected Illness

Meerson FZ (1983) Adaptation, Stress and Prophylaxis

Mackenzie MA et al (1991) Poikilothermia in Man: pathophysiology and clinical implications. Medicine (baltimore)

Kreher JB, Schwartz JB (2012) Overtraining Syndrome: A practical Guide. Sports Health

Frank CL (1992) The Influence of Dietary fatty Acids on Hibernation by Golden-mantled Ground Squirrels. Physiological Zoology

Cramer DL, Brown JB (1943) The Component Fatty Acids of Human Depot Fat. Journal of Biological Chemistry

Geiser F (1990) Influence of polyunsaturated and saturated dietray lipids on adipose tissue, brain and mitochondrial membrane fatty acid Composition of a mammalian hibernator. Biochimica et Biophysica Acta

Carey HV et al (2003) Mammalian Hibernation: Cellular and Molecular Responses to Depressed Metabolism and Low Tempertaure. Physiol rev

Ayre KJ, Hulbert AJ (1997) Dietary fatty acid profile affects endurance in rats. Lipids

Hulbert AJ et al (2010) Membrane fatty acid composition and longevity of mammals and birds. Research Online

Hulbert AJ  et al (2005) Dietary fats and membrane function: implications for metabolism and disease. Research Online

Zombie sleep patterns

‘Tis sleep that knits up ravell’d sleeve of care, the death of each day’s life, sore labours bath, balm of hurt minds, great nature’s second course, chief nourisher in life’s feast’

Macbeth, William Shakespeare

Def. a zombie runner is a runner with a de-energised brain (see our earlier post Zombie Runners).

Each species requires a different amount of sleep each day to maintain good health (fig 1).  On average, a young-adult human requires 8 hours a day that gradually declines to 6.5 hours a day when elderly. The inability to go to sleep (insomnia) and/or remain asleep (dyssomnia) are classic signs of stress and ‘over-training’.


There are many possible biological, psychological and social reasons for disturbed sleep patterns, but one cause that is frequently over looked in runners is deficient-night-time-liver-glycogen levels. The period of time we are asleep is known as an ‘over-night fast’ which in young, healthy adults occurs in two distinct phases (fig 2):



Stage 1: Glucose for the brain is provided almost exclusively by the breakdown of liver glycogen (depending on the timing of the last carbohydrate meal)

Stage 2:  As liver glycogen depletes, cortisol begins to rise, breaking down proteins (amino acids) in muscle (and thymus-lymphatic tissue) to maintain blood glucose via gluconeogenesis. In the healthy-well-fed liver, glycogen stores are never fully depleted, and the additional glucose provided by gluconeogenesis is enough to ensure a peaceful, undisturbed 8 hours of sleep (fig 3a). If liver glycogen stores are not fully replenished before attempting to sleep, either due to illness or unintelligent eating and training behaviour, the liver glycogen stores will be inadequate to maintain blood glucose through the night, causing an early and exaggerated cortisol response and increased gluconeogenesis. If blood glucose falls below homeostatic requirements of the brain, an ‘emergency’ adrenalin response occurs to ‘squeeze’ some extra glucose into the blood from the glycogen stores in the liver.

This rapid rise in adrenalin creates a classic ‘fight-or-flight’ stress response of increased arousal (increased cardiac output and respiration) which makes sleep impossible until the circulating adrenalin has returned to normal (fig 3b).


The ability to sleep for 7-8 hours each night is a homeostatic requirement for homo sapiens, and sleep disturbances are a reliable indication of Over Training Syndrome (OTS) and chronic stress. A basic understanding of the liver’s role as the ‘glucostatic’ organ, and how to restore and support it’s function, is essential knowledge for anyone involved in training athletes, and is considered an essential part of the BTR bioenergetics education.


Cannon. W. (1932) The Wisdom of the body

Frayn K N. (1996) Metabolic Regulation: A human perspective

Armstrong L.E., VanHeest J.L (2002). The Unknown mechanism of the Overtraining Syndrome. Sports Med

Scheer et al (2010) Impact of the human circadian system, exercise, and their Interaction on cardiovascular function. PNAS

Macauley et al (2015) Diurnal variation in skeletal muscle and liver glycogen in humans with normal health and type 2 diabetes. Clinical science.

Zombie Runners


“The third or chronic form of general fatigue is found in men during a course of training in which the amount of endurance required daily is more than can be regained during the periods of rest. In this condition the temperature becomes subnormal, the weight goes down, the skin looks pale and flabby, the muscles lose their elasticity, the eye becomes dull and listless, interest in exercise ceases, every effort becomes a burden, and the patient sits without ambition or the power to rouse himself from his lethargy”

Exercise in Education and Medicine by Robert Tait McKenzie, B. A., M. D (1909)

zombie-runner-fig1The human brain is three times the size of an ape’s relative to body size (fig 1). It accounts for 20-25% of an adult’s resting oxygen and energy use, and 60-70% of total-body-glucose metabolism. This makes the human brain the most ‘expensive’ metabolic tissue found within all known species, and one of the most vulnerable to metabolic ‘stress’, especially during it’s growth and development (fig 2).

Despite it’s reliance on a constant supply of glucose, the brain stores only a tiny amount locally as glycogen*, so relies on the ‘glucostatic’ function of the liver (80-90% of circulating glucose comes from the liver) to maintain an adequate glucose supply. Brain function is compromised when blood glucose falls below (hypoglycemia), or exceeds (hyperglycemia), the normal physiological range (70-110 mg/dl). Consequently, humans have evolved a number of metabolic ‘emergency’ strategies to ensure the survival of the brain, often to the detriment of the rest of the body.


The progression of ‘Over Training Syndrome’, due to unintelligent-endurance training (see BTR Training Zones), shares many features with the progression of glucose starvation (fig 3). The ‘raiding’ of vital-structural and immune-system proteins, combined with the attempt to metabolise inferior ‘energy’ substrates (lactate, amino acids, and fatty acids), creates the physiological and psychological symptoms of Hysteria, Neurasthenia, Hypochondriasis, Malingering, Pyschoneurosis, Depression, Chronic Fatigue Syndrome (CFS), Myalgic Encephalopathy (ME), Post-Viral Fatigue Syndrome (PVFS), Under Performance Syndrome (UPS) and Over Training Syndrome (OTS).

These labels are historically and culturally dependent, but would appear to boil down to one thing; a de-energised brain.


* For every 1 gram of glycogen stored, 3 grams of water is stored with it so for the brain to store 100g of glycogen (the amount stored in the liver) it would weigh an additional 400g. The extra weight (and volume) would completely change the morphology and function of the human body.


Ruderman NB, Aoki TT, Cahill GF. (1976) Gluconeogenesis and its disorders in man. In Gluconeogenesis: Its Regulation in Mammalian Species.

SC Kalhan and IÁ Kilic (1999) Carbohydrate as nutrient in the infant and child: range of acceptable intake. European Journal of Clinical Nutrition.

Taylor RE (2001) Death of neurasthenia and it’s psychological reincarnation. British Journal of Psychiatry.

Lewin R. (1984) Human Evolution: An illustrated Introduction.

Muhammad Z. Shrayyef and John E. Gerich (2010) Normal Glucose Homeostasis: in Principles of Diabetes mellitus. L. Porestky (ed)

The bioenergetics of running

“Three things are needed to build and maintain a living system: material, information (pattern), and energy. There is no life without energy”

Albert Szent-Györygi The Living State (1972)

runner-pic1‘It has always been my view that a knowledge of physiology and biochemistry makes exercise more interesting for a runner. The current running boom (for some almost an addiction, but if so the only healthy addiction I know) makes necessary for the intelligent runner to know more  about his body, how hard he should train, when he should yield to fatigue and what should be his diet and what are the limiting factors of his performance…’ Sir Roger Bannister MD.

The BTR bioenergetics education has been designed in the same spirit as the BTR biomechanics education; with the intention of providing a small island of coaching wisdom in a ‘boggy’ area notoriously flooded with information i.e. training and diet.

‘The Runner’ by Eric Newsholme and Tony Leech was the starting point in the creation of BTR’s ‘bioenergetics’ and although first published in 1983 the knowledge contained within this small book and it’s 150 pages is still very relevant today (as the preface from Sir Roger Bannister above indicates). Here are a few examples of the simple Figures used and BTR’s interpretation of them.


Running A Marathon:

runner-pic2A healthy-human body contains enough stored glucose (glycogen) to provide energy for approximately 90 mins of running. Consequently, the body must use an alternative fuel source to provide energy for runs of longer duration. The substrate of choice is fatty acids. (*Gluconeogenesis from structural proteins is an ‘expensive’ option that the body will try to avoid whenever possible)

The ‘Wall’:

runner-pic3Up to the 17th-18th mile, the average runner has been oxidising both fatty acids and glucose. The muscle glycogen stores are now depleted, and fatty-acid oxidation cannot provide ATP at the rate required to maintain the desired muscle action and running speed, consequently the pace drops and the pain increases.

Fatty acids; A vicious cycle:

runner-pic4Using fatty acids as as a fuel is a ‘survival’ strategy designed to conserve enough liver glycogen to prevent hypoglycemia and maintain brain function. The glucose-sparing effect of fatty acid oxidation observed in well-trained distance runners is also consistently observed in shock, starvation, heart failure and diabetes and is known as the ‘Randle cycle’.

The Good, The Bad, The Ugly PART 2: Squatting

“A ship is safe in harbor, but that’s not what ships are for”

William Shedd

real-squatIf there is one exercise that runners should become obsessed about, it is the deep squat. It is no coincidence that the naturally-resilient-running populations discussed in PART 1 not only have ‘foot-shaped feet’ but also regularly adopt a deep-squatting posture as a ‘rest position’ for all sorts of daily activities. These people are not super human but have simply  maintained the squat position that all humans use until 3-5 years old, before the culture of chairs and sitting began to take over. (see The Human Sea Squirt)


BTR-SQUAT-GOODDef. The habitual-squatting position of homo sapiens.

This position should not be considered an ‘athletic’ position, but rather a fundamental human movement akin to standing and walking. The ability to adopt the ‘good’ deep-squat position indicates healthy ankle, knee and hip function and has many benefits for runners, including the development and maintenance of full range of motion (ROM) in the joints required for ‘good’ running technique. The ‘good’ deep squat is a fundamental motor skill milestone for BTR, and mastering this skill is an essential part of the ‘Bulletproof Runner’ protocol.


BTR-SQUAT-BADDef. The habitual squatting position of homo sedentarius, endorsed by chartered physiotherapists and certified personal trainers worldwide as the ‘safest’ way to squat.

The ‘bad’ squat appears ‘safe’ due to the limited range of motion required at the ankle, knee and hip to perform this movement, but when these limitations (known as ‘sagittal blocks’) manifest in dynamic-human movements such as jumping, walking and running, the body compensates with unnatural movement strategies and destructive loading patterns e.g. over pronation and over striding (see overstriding).


BTR-SQUAT_UGLYDef. The habitual-squatting position of homo neanderthalensis and ‘cross-fitters’.

The ‘ugly’ deep squat is the equivalent of the ‘ugly’ running style (see good bad ugly part 1) in that it is performed and coached with good intentions, but probably causes as many problems for runners as the ‘bad’ squat. The limited range of movement (ROM) at the ankle joint (observe the knee position relative to ankle position in the diagram left) means that compensatory movement must occur in the lumbo-pelvic region in order to adopt a deep-squatting position. The compromised alignment of the ‘ugly’ deep squat places the pelvis and lower back in an extremely-vulnerable position where the addition of extra weight and/or higher velocities (weightlifting and plyometric routines) will invariably add a ‘bad back’ to your list of ‘running injuries’.

Page 1 of 3123