Phosphocreatine is a high-energy storage molecule found within skeletal muscle. During intense exercise, phosphocreatine provides immediate replenishment of ATP (Adenosine-5′-triphosphate), which transports chemical energy from within cells for metabolic processes.

Traditional endurance training induces physiological adaptations such as improved aerobic capacity, along with a reduction in glycogen utilization and lactate accumulation. HITT has been shown to be an efficient way to produce similar effects.

Multiple HIIT bouts are designed to deplete phosphocreatine stores in the working skeletal muscle, and so reducing power output.

It takes more than six minutes to fully recover phospho-creatine stores after exercise-induced depletion. Therefore, if recovery intervals during HIIT bouts are less than six minutes, phosphocreatine may not be fully replenished, leading to a reduced performance.

Supplementing with creatine has been demonstrated to effectively increase muscle phosphocreatine stores. Specifically, one study showed a 20% increase in muscle creatine with ingestion of 20 g of creatine per day for just 5 days.

The purpose of the study published in the Journal of the International Society of Sports Nutrition was to determine the effects of high-intensity interval training and creatine supplementation on cardiorespiratory fitness and endurance performance.

The subjects were 43 college-aged men who typically performed 1-5 hours of exercise per week. None had taken sports supplements, including any form of creatine, in the three months prior to the beginning of the study.

Participants were randomly assigned to a creatine or a placebo group and supplemented for 30 days at a dose of 10 g per training day, taken in two doses – one dose 30 minutes prior to and one dose immediately following training.

• Creatine group consumed 5 g of creatine citrate mixed with 15 g dextrose
• Placebo group consumed 20 g of dextrose

A control group, consumed no supplements nor completed the high-intensity interval training, and instead only completed the testing measurements.

Participants performed HIIT five days per week, for six weeks at progressively increasing workloads, determined as a percentage of the participant’s baseline VO_2PEAK max workload. Training increased in intensity each session beginning at 90% of their VO_2PEAK max workload and progressing up to 120% of their VO_2PEAK max workload.

Each training session began with a five-minute warm up, followed by a protocol of five sets of two-minute exercise bouts, with one minute of passive rest in between exercise bouts.

A maximal graded exercise test on a cycle ergometer was used to determine:

• maximal oxygen consumption (VO_2PEAK)
• maximum heart rate (HRmax).
• total work done (TWD)
• time to exhaustion (VO_2PEAKTTE)
• ventilatory threshold (VT), this is the point during graded exercise in which venitilation increases disproportionately to oxygen uptake.

Endurance performance is commonly assessed using a measure of aerobic capacity. While the HIIT program was effective in improving maximal oxygen consumption by 9%, creatine supplementation had no further influence on aerobic capacity. Ventilatory Threshold (VT) is another useful predictor of endurance performance as an indicator of the ability of the cardiovascular system to adequately supply oxygen to the working muscles. Performing exercise at intensities greater than VT often result in an inadequate supply of oxygen to the working muscles, quickly leading to fatigue.

If VT can be improved it could increase the time to exhaustion, reduce fatigue, and may enhance the efficiency of the body to supply oxygen to the working muscles.

However, when measuring VT in this study, significant improvements were only observed in the creatine group (16%), although the placebo group demonstrated a trend for improved VT (10%).

The researchers from University of Oklahoma found that HITT is an effective way to improve maximal endurance performance. The study also demonstrated an improvement to time to exhaustion with HIIT. However, whilst adding the use of creatine did improved ventilatory threshold, it did not increase total work done.

Previous studies have shown improvements in TWD after creatine supplementation which included a loading phase (20 g/d for 5-7 days). A loading phase was not used in the current study, so it may be possible that muscle phosphocreatine levels were not increased enough to aid in improving TWD.

The researchers did suggest that it is possibile that any benefits of low-dose creatine supplementation were masked by the effectiveness of HIIT alone.

This new research, published in the Proceedings of the National Academy of Sciences (PNAS), focused on young adults and revealed that those who are physically fit, have a higher IQ and are more likely to go to university.

The researched studied 1.2 million Swedish men born between 1950-1976, who were enlisted for military service at 18. Physical fitness and intelligence performance data was collected during conscription examinations and linked with other national databases for information on school achievement, socioeconomic status and sibship.

After adjusting for relevant confounders there was a positive association with intelligence with cardiovascular fitness as measured by ergometer cycling.

Good physical fitness provided the strongest association with logical thinking and also verbal comprehension. Only cardiovascular fitness was found to play a role in the results of the IQ test, in contrast strength was not linked with cognitive performance.

“Being fit means that you also have good heart and lung capacity and that your brain gets plenty of oxygen,” says Michael Nilsson, professor at the Sahlgrenska Academy and chief physician at the Sahlgrenska University Hospital. “This may be one of the reasons why we can see a clear link with fitness, but not with muscular strength.”

Relationships between cardiovascular fitness and intelligence at age 18 were also evaluated and compared between twins and other siblings

Analysis between siblings suggested less than 15% was due to heritable factors and >80% of the cardiovascular intelligence association was due to environmental factors rather than genes to explain the link between fitness and a higher IQ.

The study also showed that cardiovascular fitness changes between ages 15-18 predict cognitive performance at 18. The researchers suggest that physical education is a subject that has an important place in schools and is an absolute must if we want to do well in maths and other theoretical subjects. This is interesting as certainly in my experience, I got to opt out of school physical exercise at age 15 by choosing to go 10 pin bowling or ice skating. I certainly did do anything that would improve my cardiovascular fitness at school.

Cardiovascular fitness at age 18 was also found to predict educational achievements later in life. The researchers compared the socioeconomic status of the men later in life and found that those who were fit at 18 were more likely to go into higher education and secured more qualified jobs.

Author Maria A. I. Åberg concluded that physical exercise could be an important instrument for public health initiatives to optimize educational achievements, cognitive performance, as well as disease prevention at the society level.

Whilst exercise while young positively affects peak bone mass, exercise during adulthood can maintain bone mass and can potentially prevent women from osteoporosis.

In particular, impact exercise that induces high strains at high rates in the bone has been found to promote bone strength.

Research published in November’s BMC Musculoskeletal Disorders, studied how bone changes over time during a 12 month course of exercise.

The aim was to evaluate the association between exercise intensity at 3, 6 and 12 month intervals and changes  in the Bone Mineral Density (BMD) of the femur (thigh bone), during high-impact exercise in premenopausal women.

• The subjects were 35 healthy women (age 35-40 years, average BMI of 25.5). Before the study began they were not participating in impact-type exercises or long-distance running more than three times a week.
• Accelerometers, (portable, cheap, light-weight machines, worn on the waist) were used to continuously measure daily physical activity.
• The subjects were supervised during a 60-minute training workout, consisting of a warm-up period, high-impact training and a cool-down period. The progressive high-impact period included versatile movements, such as step aerobic patterns, stamping, jumping, and running, three times a week for 12 months.
• The programs were modified bimonthly to become progressively more demanding by including higher jumps and drops.
• The participants were also given a home program (10 min daily), which consisted of patterns of exercise similar to those in the supervised sessions.
• The BMD of the femur, and the trochanters (the projections from the femur where the hip and thigh muscles attach), were measured using x-ray absorptiometry and activity data was correlated with changes in bone density.

The researchers from Finland found that the average daily number of high impacts during six months of training was significantly associated with 12-month positive BMD changes at the femoral neck and trochanter area.

These results agreed with many previous studies, in which only five to six months of high-impact exercise were needed to increase BMD in the femoral neck and trochanter and the greatest changes were seen on this time period, than during 12 or 18month interventions.

Lead author Riikka Ahola, suggests these results provide new information for designing optimal and feasible training programs that can prevent bone loss in premenopausal women

Because bone cells adapt to regular loading, one important feature that the researchers recommend is for an exercise program to be progressive. ‘A progressive exercise program sustains overload and the bone adaptation process. ‘

‘Loads should be increased with time to produce a sufficient stimulus. An exercise program that maintains the same loading for many years would stimulate bone formation only during the first months of training.’

Depending on which article you read in the press ‘Calorie count guidance may rise by a cheeseburger’ or ‘two bags of ready salted crisps’. Personally I would see it as 4 bananas, 8 apples, or 16 satsumas, but they seem less headline grabbing.

The headlines are based on a draft report prepared for consideration by the Scientific Advisory Committee on Nutrition (SACN). Current daily calorie recommendations are based on the ‘Estimated Average Requirement’ (EAR) published in 1991, but following a new method of calculating how much energy we use the SACN report suggests that even for inactive people this has been under estimated. The new findings imply that the current recommended daily intake of 2000 calories for women and 2500 for men could be increased by up to 16% so an extra 320 for women and 400 for men.

Whilst the report does acknowledge that the previous calculated EAR was incorrect, the authors do not suggest that everyone should be told they can eat more. In fact they suggest that education of people regarding calorie intake is necessary.

The report highlights that according to the National Diet and Nutrition Survey (NDNS) the amount of food people admit to eating is consistently below the previous daily calorie guidelines. However the NDNS and other surveys of the UK population show the number people classified as overweight or obese is increasing.  This can probably be explained by a combination of excess eating and inactivity.

The SACN report actually states ‘The high prevalence of overweight and obesity in the UK population shows that, for the majority of people, energy intakes are in excess of energy requirements. It is important that the proposed Estimated Average Requirement values are not used to signal or encourage an increase in energy intake of the population as a whole: this would increase the prevalence and magnitude of overweight and obesity in the absence of a corresponding increase in energy expenditure’.

We are already aware that the energy requirements for an individual depend on a number of factors including age, gender, body size and composition, pregnancy, and physical activity. A petite, 70 year old sedentary woman is not going to need as much energy as a tall 35 year old mother constantly running around with her small children.

So unfortunately this research is only acknowledging there is a more accurate method for calculating energy needs and does not mean we are all given a green light to eat more. We probably underestimate just how much we eat already, so we should instead increase our energy expenditure to follow the recommended 30minutes of moderate intensity exercise 5 times a week, and ignore the newspaper headlines.

A study by Donald Redelmeier and Ari Greenwald published in the British Medical Journal randomly selected 26 marathons in the US with more than 1000 participants and followed each for up to 30 years from 1975- 2004. This amounted to 750 marathons and 3,292,268 participants encompassing 14 million hours of exercise. Over the 30 years there were 26 sudden cardiac deaths equivalent to 0.8 per 100,000 participants. The typical participant with sudden cardiac death was a middle aged man (average age 41 years, 81% men). 5 deaths were in individuals who had previously completed a marathon, with the most common location of death at or within 1mile of the finish. The risk of sudden cardiac death equated to about 2 deaths per million hours of exercise.

Whether due to the increase in popularity of marathon events or the increase in previously inactive people ‘wanting to have a go at one’ the incidences of deaths in marathons have increased in recent years.  Deaths during marathon events are generally due to 4 factors:

• Heart Disease - One of the common causes of death in marathon runners due to heart attacks brought about by underlying coronary artery disease. These attacks are brought on by a combination of the physical stress of the event combined with the person’s lack of cardiac fitness.
• Sudden Cardiac Death - On average 12 young people a week die from sudden cardiac death. In 2007 the 28 year old professional runner Ryan Shay collapsed during the Olympic marathon trials. Ryan was young and highly trained and had previously run 7 marathons. His autopsy reported the cause of death to be Cardiac arrhythmia due to cardiac hypertrophy, meaning abnormal beating due to an enlarged heart.
• Water Intoxication - This occurs when there is so much water in the body that it dilutes vital minerals such as salt to dangerous levels. It can lead to confusion, headaches and fatal swelling of the brain. In 2007 22yr old fitness instructor David Rogers died from hypomatraemia after completing the London Marathon.
• Heat stroke - This is brought about by extreme dehydration. Learning to regulate body heat is important, rehydrating efficiently without becoming intoxicated by too much fluids. In the 2005 Great North Run half marathon four male runners died due to heat related illnesses.

Of the 24 autopsy reports available in Redelmeier’s study there were 21 cases of atherosclerosis, contributing factors included (2) coronary anomalies, (4) electrolyte abnormalities and (1) heat stroke.

People should not be discouraged from running full or half marathons as the health benefits of regular exercise by millions of people out weigh the tragic sudden deaths of a few participants. Whilst some deaths are medically related, a number of people who require emergency medical attention do so because they do not respect the marathon event.

My first marathon should have been a Golden Bond place in the London Marathon. The day before the race I awoke to my entire body and face swollen and red. A visit to the doctor revealed I just had a virus or allergic reaction to something and was advised not to run as I would be putting added to strain on my body attempting to complete a marathon while fighting an infection. Whilst being bitterly disappointed in missing the race I was persuaded that by running I was not only risking my own health but those of other runners if the medical teams had to treat me rather than another casualty. Three weeks later I was able to successfully run a different marathon, collect sponsorship for my chosen charity and I got a ballot place for London the following year.

Celebrities such as Katie Price, being praised for completing the race whilst still suffering from the effects of a miscarriage days earlier, or Jade Goody, admitting to have done no training but congratulated for making it to mile 18, just suggest to the public who ‘fancy a go’ that the marathon is not too much of a physical challenge and doesn’t need to be taken seriously. Thankfully there are celebrities such as Nell McAndrew, Tom Audenshaw and Gordon Ramsey who show commitment to their training, health and race performance.

Whilst deaths associated with marathons are rare, if anything can be done to reduce them even more, it should be implemented. In Italy before participating in a marathon runners are required to complete a medical sports fitness test including an electrocardiogram (ECG). Although it may seem an expensive inconvenience if this was extended to other countries this may identify those at risk of cardiac related conditions and save lives. Additionally if required to provide evidence that you have trained sufficiently or participated in at least  a half marathon, runners will have at least experienced some physical stress of endurance exercise and had the chance to learn how to deal with heat and efficiently rehydrate.

ASA claim this advert was misleading

Today’s upholding of a complaint by the Advertising Standards Authority (ASA) supports my view that you should investigate claims of health benefits of products you supplement your diet with, to ensure you don’t waste your time, money or even damage your health.

The TV advert in question is for Actimel, a pro-biotic drinking yoghurt intended to be consumed by every one of all ages. One viewer had challenged whether the claim by the ad voice-over that “Actimel was scientifically proven to help support your kids’ defences” could be substantiated.

In their defence to the ASA, Danone claimed that the health benefits of Actimel had been demonstrated in 23 human studies conducted on over 6000 people across different age ranges, with eight studies carried out on children up to 16 years of age.

Danone claimed that the health benefit of Actimel is through the support of the human body’s natural defence system, helping to protect against pathogens and harmful environmental factors, as some of the most important defence systems are located within the gastrointestinal tract. Danone said they had referred to Actimel as being “scientifically proven” in their ads based on a significant body of published scientific evidence that showed that Actimel supported the natural defences of different age groups, including children.

The ASA thought that the ad suggested through the image of an Actimel bottle jumping over a skipping rope and the sound of children laughing and playing implies that the product is intended for normal, healthy children of school age (five to sixteen years old). The ASA also considered that most consumers would understand the claim that Actimel “was scientifically proven to support your kids’ defences” to mean that the product would help defend those children against common, every-day childhood infections. Whilst Danone submitted scientific studies in support of the claims, they were not involving subjects who could be considered ‘normal, healthy children of school age’.

• One study examined the effect of Actimel on hospitalised children in India suffering from acute diarrhoea another involved those receiving medication for chronic Helicobacter pylori. Both trials were considered to be unsuitable for use in support of a claim that was likely to be seen as referring to normal, healthy children.
• Children in another study assessed the effect of Actimel on the occurrence and duration of a range of symptoms, including asthma, rhinitis, diarrhoea, nausea and vomiting, abdominal pains and fever, in children aged two to five years who suffered from allergic conditions. Again meaning the results of the study could not necessarily be applied to normal, healthy children.
• Three other trials were on children between the ages of 6 and 33 months, much lower than the target group of school-age children suggested by the ad. The ASA understood that the developing immune systems of children under two differed from those of older children, and so did not think that it could be safely assumed that the results reported for the young children in these studies would be the same for school-aged children.
• A further area of concern was the portion sizes used in the studies. The children in some studies were supplemented with portion sizes that were larger than the recommended serving size of one 100 g pot of Actimel per day. The observed benefit for Actimel in the clinical trials might not therefore, be representative of the effect of the product when consumed on an ‘everyday’ basis.

The ASA considered that the ad was making an absolute claim that Actimel would support the defences of children, and that the reference to “your kids” was implying to consumers that Actimel would benefit their child.

The ASA understood that some children would not see a benefit from consuming Actimel, and because were concerned that any observed effects for Actimel in the trials might not be representative of the efficacy of the product when consumed in line with the recommended daily serving. It was concluded that a serving of Actimel was not scientifically proven to support the defences of normal, healthy school-aged children against common, every-day childhood infections and that the ad was misleading.

The ASA have ruled that the ad must not be broadcast again in its current form. Whilst there is no suggestion that this product could damage anyone’s health, the findings of the ASA support my previous articles on supplement efficacy and safety: Even with claims of supporting scientific evidence, many products may only benefit specific groups of people. Before you waste your money on ‘healthy’ products, consider if you are actually deficient in the nutrients they are supplying?  If they can cure illnesses, is it something you are suffering from? Do you fit the target group scientific studies have shown benefit in? If in any doubt consult a healthcare professional.