Latest News & Research: 15 October 2019

This week: Excessive exercise may lead to poor decision making • Fast food leads to slow testosterone • Regular exercise benefits heart, regardless of age


Fast food leads to slow testosterone

Obese men hoping to one day become fathers should take note of this new finding from Aussie researchers. Obesity is known to be associated with impaired testicular function, potentially resulting in androgen deficiency and sub-fertility. Now it is clear that fast food meals consumed by obese or overweight men have an immediate negative impact on testicular performance and testosterone production.

While many factors are involved in the underlying cause of obesity-related male hypogonadism, Flinders University and UniSA researchers have found that a high fat intake from ‘fast food’ meals has a decisive negative effect on a man’s serum testosterone levels.

Their investigation into the impact of dietary fat on testicular endocrine function showed some alarming results. They found that the ingestion of a high-fat Fast Food mixed meal, which is a common practice for obese men, produced a 25% fall in serum testosterone within an hour of eating, with levels remaining suppressed below fasting baseline for up to 4 hours.

These results – which only investigated the impact on overweight and obese men, and therefore may not apply to lean men – suggest that the passage of fat through the intestinal tract elicits a response that indirectly elicits a post-prandial fall in testosterone.

‘The observed falls in serum testosterone (25% decline from baseline, 2–3 nmol in absolute terms) are likely to be clinically significant for the obese or older man with low baseline levels of testosterone’ said Flinders University’s Professor Kelton Tremellen, gynaecologist and Strategic Professor of Reproductive Medicine, who undertook the research with Dr Karma Pearce from UniSA.

‘These men are likely to be placed into a continuous hypogonadal state during waking hours if they frequently consume meals and snacks high in fat. This will clearly have an adverse impact on both their mental and physical wellbeing, plus possibly their fertility potential. Our results suggest that these men should minimise their fat intake and avoid inter‐meal snacking in order to optimise testicular function.’

Source: Flinders University


Regular exercise benefits heart, regardless of age

Regular exercise is highly beneficial for all patients with cardiovascular disease regardless of age, report investigators in the Canadian Journal of Cardiology, published by Elsevier. Their results showed that the patients who benefited most from cardiac rehabilitation were those who started out with the greatest physical impairment.

Elderly patients are at a higher risk for complications and accelerated physical deconditioning after a cardiovascular event, yet older patients are largely underrepresented in rehabilitation programs. Studies have shown that this might be due to a lack of referral and encouragement to attend cardiac rehabilitation in older patients.

‘Ageing is associated with several factors, such as increased inflammation or oxidative stress that predispose people to cardiovascular diseases. As a result, elderly patients are usually less fit than their younger counterparts, and deconditioning is accelerated once cardiovascular disease is established’ explained lead investigator Gaëlle Deley, PhD from the Faculty of Sports Sciences, University of Burgundy Franche-Comté in France; ‘However, there are few data about the impact of patient age on the physical and psychological effectiveness of cardiac rehabilitation.’

Several studies have looked at the effects of cardiac rehabilitation in older adults. However, these data often focus on patients above the age of 65 with no distinction between old and very old patients and examine either physical or psychological outcomes, but not both.

The goal of this study was to compare the effects of an exercise-based cardiac rehabilitation program on physical and psychological parameters in young, old, and very old patients. It also aimed to identify the features that best predicted cardiac rehabilitation outcome.

All patients referred to Cardiac Rehabilitation at the Clinique Les Rosiers, Dijon, France from January 2015 to September 2017 were included in this single-centre prospective study. Investigators examined 733 patients who completed a 25-session cardiac rehabilitation program. They were divided into three subgroups: less than 65 years old; between 65 and 80 years old; and 80 years or older. Physical and psychological variables, such as scores of anxiety and depression, were evaluated for all patients before and after cardiac rehabilitation.

Following the intervention, all patients experienced improvements; ‘We found a few weeks of exercise training not only significantly improved exercise capacity, but also decreased anxiety and depression. Patients with the greatest physical impairments at baseline benefited the most from exercise’ commented Deley; ‘Another interesting result was that patients younger than 65 who were very anxious before rehabilitation benefited the most from exercise training. A similar result was found for depressed patients older than 65. These improvements will surely have a great positive impact on patients' independence and quality of life and might help both clinicians and patients to realise how beneficial exercise rehabilitation can be.’

In an accompanying editorial, Codie R. Rouleau, PhD, RPsych, Clinical Psychologist, Adjunct Assistant Professor in Psychology, and James A. Stone, MD, PhD, Clinical Professor of Medicine, both at the University of Calgary and Total Cardiology Research Network in Calgary, AB, Canada, point out that the study's conclusion that age does not limit physical performance outcomes is inconsistent with some previous research showing that advancing age, especially for patients 60 years and older, is associated with smaller cardiorespiratory fitness gains during cardiac rehabilitation. The reasons may relate to different program characteristics, different methods of physical performance measurement, or the exceptional adherence rate reported in the study (average 98.6% prescribed sessions attended).

‘Older adults who are eligible for cardiac rehabilitation have a decreased likelihood of receiving a referral compared to their younger counterparts and the present report may serve as a catalyst for clinicians to recognise that older adults with coronary artery disease stand to benefit only if referred and given the opportunity to participate’ commented Rouleau.

‘A strength of this work is the examination of changes in psychosocial well-being during cardiac rehabilitation – an understudied outcome that is often highly valued by patients’ added Stone; ‘The work of Deley et al. may help inform strategies to augment the effects of rehabilitation, reach more patients with a greater likelihood of achieving clinical benefit, and derive improved outcomes from higher value healthcare.’

Cardiovascular diseases are the main cause of death globally. Nearly 18 million people died from cardiovascular diseases in 2016, representing over 30% of all global deaths according to the World Health Organization. While cardiovascular diseases increasingly affect young people, the number of people above the age of 65 years, and even more above the age of 80 years, dying from cardiovascular diseases is also increasing.

Source: EurekAlert!


Excessive exercise may lead to poor decision making

A new French study has found that over-exercising might reduce our capacity to make decisions.

Researchers at Hôpital de la Pitié-Salpêtrière in Paris, found that overtraining syndrome may affect the brain, as well as the rest of the body. Overtraining syndrome is a form of burnout in endurance athletes. It occurs as a result of intensive physical training overload.

The authors believe that this form of fatigue may involve some of the same neural circuitry as the fatigue that follows intensive intellectual work. Scientists have already found that fatigue following excessive mental effort can affect cognitive control, which is a person's ability to change their behaviour and thought processes to achieve their goals.

A physical training overload leads to a significant drop in physical performance as athletes experience an overwhelming sense of fatigue. The researchers wanted to test whether overtraining syndrome arises in part from neural fatigue in the brain, as well as from muscle tiredness. They were also interested in whether the overtraining affected the same portion of the brain as excessive intellectual work.

The group recruited 37 competitive male endurance athletes with an average age of 35 years. The participants either continued with their regular exercise regimen or increased their training by 40% per session over 3 weeks.

The athletes participated in cycling exercises on their rest days so that the researchers could monitor their physical performance. They also completed questionnaires that asked them about their subjective experience of fatigue. Finally, the researchers used behavioural tests and MRI scans to assess the participants' cognitive ability.

The study, which features in Current Biology, showed that over 3 weeks, physical training overload led to the athletes feeling more fatigued and also behaving differently. In tests that evaluated economic choices, the fatigued athletes were more likely to act impulsively.

MRI scans showed that physically overloading the athletes resulted in impaired activation of the lateral prefrontal cortex. This area of the brain is responsible for higher order cognitive control; it influences decision-making, planning, behavioral inhibition, and motivational operations, among other behaviours.

Motivational operations are particularly interesting because they define how the brain processes reward information. This study's findings show that athletes who experienced physical overload were more likely to act impulsively. Specifically, they opted for immediate rewards rather than rewards that were more significant but would take longer to achieve.

This study is the first to demonstrate that physical training can also induce cognitive fatigue. In their paper, the authors ask whether their findings might help explain why endurance athletes have a higher likelihood of doping. They note that doping ‘may help with immediate performance but compromise long term achievements.’

If training overload increases impulsivity and decreases the capacity to resist the temptation of immediate reward, the authors wonder whether this could have important consequences outside of sport. The authors were particularly struck by the fact that both physical overload and excessive intellectual work affect the same area of the brain.

The corresponding author, Mathias Pessiglione, explains, ‘This brain region, therefore, appeared as the weak spot of the brain network responsible for cognitive control. You need to control the automatic process that makes you stop when muscles or joint hurts.’

It is worth noting that this study only involved a small group of participants. Researchers will need to carry out further experiments using larger cohorts to assess whether this is a genuine effect. Also, because the scientists only recruited people who were physically fit, it is not clear whether people at other levels of fitness might also experience this effect.

Source: Medical News Today