Is Exercise Protective Against Influenza-Associated Mortality?

Background

Little is known about the effect of physical exercise on influenza-associated mortality.

Methods and Findings

We collected information about exercise habits and other lifestyles, and socioeconomic and demographic status, the underlying cause of death of 24,656 adults (21% aged 30–64, 79% aged 65 or above) who died in 1998 in Hong Kong, and the weekly proportion of specimens positive for influenza A (H3N1 and H1N1) and B isolations during the same period. We assessed the excess risks (ER) of influenza-associated mortality due to all-natural causes, cardiovascular diseases, or respiratory disease among different levels of exercise: never/seldom (less than once per month), low/moderate (once per month to three times per week), and frequent (four times or more per week) by Poisson regression. We also assessed the differences in ER between exercise groups by case-only logistic regression. For all the mortality outcomes under study in relation to each 10% increase in weekly proportion of specimens positive for influenza A+B, never/seldom exercise (as reference) was associated with 5.8% to 8.5% excess risks (ER) of mortality (P<0.0001), while low/moderate exercise was associated with ER which were 4.2% to 6.4% lower than those of the reference (P<0.001 for all-natural causes; P = 0.001 for cardiovascular; and P = 0.07 for respiratory mortality). Frequent exercise was not different from the reference (change in ER −0.8% to 1.7%, P = 0.30 to 0.73).

Conclusion

When compared with never or seldom exercise, exercising at low to moderate frequency is beneficial with lower influenza-associated mortality.     

Chronic Obstructive Pulmonary Emphysema—Is Exercise Beneficial?

Following a six-week program of training in a series of exercises, a significant number of patients with chronic obstructive pulmonary emphysema showed decided improvement in functional activity. Subjective improvement also was noted and kept the patient motivation high.Preliminary observations indicated that the improvement could be maintained long after the end of the training period.     

Is the Effect of Aerobic Exercise on Cognition a Placebo Effect?

A number of studies and meta-analyses conclude that aerobic fitness (walking) interventions improve cognition. Such interventions typically compare improvements from these interventions to an active control group in which participants engage in non-aerobic activities (typically stretching and toning) for an equivalent amount of time. However, in the absence of a double-blind design, the presence of an active control group does not necessarily control for placebo effects; participants might expect different amounts of improvement for the treatment and control interventions [1]. We conducted a large survey to explore whether people expect greater cognitive benefits from an aerobic exercise intervention compared to a control intervention. If participants expect greater improvement following aerobic exercise, then the benefits of such interventions might be due in part to a placebo effect. In general, expectations did not differ between aerobic and non-aerobic interventions. If anything, some of the results suggest the opposite (e.g., respondents expected the control, non-aerobic intervention to yield bigger memory gains). These results provide the first evidence that cognitive improvements following aerobic fitness training are not due to differential expectations.     

Activation of AMPKα2 Is Not Required for Mitochondrial FAT/CD36 Accumulation during Exercise

Exercise has been shown to induce the translocation of fatty acid translocase (FAT/CD36), a fatty acid transport protein, to both plasma and mitochondrial membranes. While previous studies have examined signals involved in the induction of FAT/CD36 translocation to sarcolemmal membranes, to date the signaling events responsible for FAT/CD36 accumulation on mitochondrial membranes have not been investigated. In the current study muscle contraction rapidly increased FAT/CD36 on plasma membranes (7.5 minutes), while in contrast, FAT/CD36 only increased on mitochondrial membranes after 22.5 minutes of muscle contraction, a response that was exercise-intensity dependent. Considering that previous research has shown that AMP activated protein kinase (AMPK) α2 is not required for FAT/CD36 translocation to the plasma membrane, we investigated whether AMPK α2 signaling is necessary for mitochondrial FAT/CD36 accumulation. Administration of 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR) induced AMPK phosphorylation, and resulted in FAT/CD36 accumulation on SS mitochondria, suggesting AMPK signaling may mediate this response. However, SS mitochondrial FAT/CD36 increased following acute treadmill running in both wild-type (WT) and AMPKα 2 kinase dead (KD) mice. These data suggest that AMPK signaling is not required for SS mitochondrial FAT/CD36 accumulation. The current data also implicates alternative signaling pathways that are exercise-intensity dependent, as IMF mitochondrial FAT/CD36 content only occurred at a higher power output. Taken altogether the current data suggests that activation of AMPK signaling is sufficient but not required for exercise-induced accumulation in mitochondrial FAT/CD36.     

Telomere Length and Long-Term Endurance Exercise: Does Exercise Training Affect Biological Age? A Pilot Study

Background

Telomeres are potential markers of mitotic cellular age and are associated with physical ageing process. Long-term endurance training and higher aerobic exercise capacity (VO_2max) are associated with improved survival, and dynamic effects of exercise are evident with ageing. However, the association of telomere length with exercise training and VO_2max has so far been inconsistent. Our aim was to assess whether muscle telomere length is associated with endurance exercise training and VO_2max in younger and older people.

Methods

Twenty men; 10 young (22–27 years) and 10 old (66–77 years), were studied in this cross-sectional study. Five out of 10 young adults and 5 out of 10 older were endurance athletes, while other halves were exercising at a medium level of activity. Mean telomere length was measured as telomere/single copy gene-ratio (T/S-ratio) using quantitative real time polymerase chain reaction. VO_2max was measured directly running on a treadmill.

Results

Older endurance trained athletes had longer telomere length compared with older people with medium activity levels (T/S ratio 1.12±0.1 vs. 0.92±0.2, p = 0.04). Telomere length of young endurance trained athletes was not different than young non-athletes (1.47±0.2 vs. 1.33±0.1, p = 0.12). Overall, there was a positive association between T/S ratio and VO_2max (r = 0.70, p = 0.001). Among endurance trained athletes, we found a strong correlation between VO_2max and T/S ratio (r = 0.78, p = 0.02). However, corresponding association among non-athlete participants was relatively weak (r = 0.58, p = 0.09).

Conclusion

Our data suggest that VO_2max is positively associated with telomere length, and we found that long-term endurance exercise training may provide a protective effect on muscle telomere length in older people.     

DEMO-II Trial. Aerobic Exercise versus Stretching Exercise in Patients with Major Depression—A Randomised Clinical Trial

Background

The effect of referring patients from a clinical setting to a pragmatic exercise intervention for depressive symptoms, cognitive function, and metabolic variables has yet to be determined.

Methods

Outpatients with major depression (DSM-IV) were allocated to supervised aerobic or stretching exercise groups during a three months period. The primary outcome was the Hamilton depression score (HAM-D₁₇). Secondary outcomes were cognitive function, cardiovascular risk markers, and employment related outcomes.

Results

56 participants were allocated to the aerobic exercise intervention versus 59 participants to the stretching exercise group. Post intervention the mean difference between groups was −0.78 points on the HAM-D₁₇ (95% CI −3.2 to 1.6; P = .52). At follow-up, the participants in the aerobic exercise group had higher maximal oxygen uptake (mean difference 4.4 l/kg/min; 95% CI 1.7 to 7.0; P = .001) and visuospatial memory on Rey’s Complex Figure Test (mean difference 3.2 points; 95% CI 0.9 to 5.5; P = .007) and lower blood glucose levels (mean difference 0.2 mmol/l; 95% CI 0.0 to 0.5; P = .04) and waist circumference (mean difference 2.2 cm; 95% CI 0.3 to 4.1; P = .02) compared with the stretching exercise group.

Conclusions

The results of this trial does not support any antidepressant effect of referring patients with major depression to a three months aerobic exercise program. Due to lower recruitment than anticipated, the trial was terminated prior to reaching the pre-defined sample size of 212 participants; therefore the results should be interpreted in that context. However, the DEMO-II trial does suggest that an exercise program for patients with depression offer positive short-term effects on maximal oxygen uptake, visuospatial memory, fasting glucose levels, and waist circumference.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00695552","term_id":"NCT00695552"}}NCT00695552     

Dissociation of Increases in PGC-1α and Its Regulators from Exercise Intensity and Muscle Activation Following Acute Exercise

Muscle activation as well as changes in peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) following high-intensity interval exercise (HIIE) were examined in young healthy men (n  = 8; age, 21.9±2.2 yrs; VO₂peak, 53.1±6.4 ml/min/kg; peak work rate, 317±23.5 watts). On each of 3 visits HIIE was performed on a cycle ergometer at a target intensity of 73, 100, or 133% of peak work rate. Muscle biopsies were taken at rest and three hours after each exercise condition. Total work was not different between conditions (∼730 kJ) while average power output (73%, 237±21; 100%, 323±26; 133%, 384±35 watts) and EMG derived muscle activation (73%, 1262±605; 100%, 2089±737; 133%, 3029±1206 total integrated EMG per interval) increased in an intensity dependent fashion. PGC-1α mRNA was elevated after all three conditions (p<0.05), with a greater increase observed following the 100% condition (∼9 fold, p<0.05) compared to both the 73 and 133% conditions (∼4 fold). When expressed relative to muscle activation, the increase in PGC-1α mRNA for the 133% condition was less than that for the 73 and 100% conditions (p<0.05). SIRT1 mRNA was also elevated after all three conditions (∼1.4 fold, p<0.05), with no difference between conditions. These findings suggest that intensity-dependent increases in PGC-1α mRNA following submaximal exercise are largely due to increases in muscle recruitment. As well, the blunted response of PGC-1α mRNA expression following supramaximal exercise may indicate that signalling mediated activation of PGC-1α may also be blunted. We also indentify that increases in PDK4, SIRT1, and RIP140 mRNA following acute exercise are dissociated from exercise intensity and muscle activation, while increases in EGR1 are augmented with supramaximal HIIE (p<0.05).     

Conducting an Acute Intense Interval Exercise Session During the Ramadan Fasting Month: What Is the Optimal Time of the Day?

This study examines the effects of Ramadan fasting on performance during an intense exercise session performed at three different times of the day, i.e., 08:00, 18:00, and 21:00?h. The purpose was to determine the optimal time of the day to perform an acute high-intensity interval exercise during the Ramadan fasting month. After familiarization, nine trained athletes performed six 30-s Wingate anaerobic test (WAnT) cycle bouts followed by a time-to-exhaustion (T_exh) cycle on six separate randomized and counterbalanced occasions. The three time-of-day nonfasting (control, CON) exercise sessions were performed before the Ramadan month, and the three corresponding time-of-day Ramadan fasting (RAM) exercise sessions were performed during the Ramadan month. Note that the 21:00?h session during Ramadan month was conducted in the nonfasted state after the breaking of the day's fast. Total work (TW) completed during the six WAnT bouts was significantly lower during RAM compared to CON for the 08:00 and 18:00?h (p?<?.017; effect size [d]?=?.55 [small] and .39 [small], respectively) sessions, but not for the 21:00?h (p?=?.03, d?=?.18 [trivial]) session. The T_exh cycle duration was significantly shorter during RAM than CON in the 18:00 (p < .017, d?=?.93 [moderate]) session, but not in the 08:00 (p?=?.03, d?=?.57 [small]) and 21:00?h (p?=?.96, d?=?.02 [trivial]) sessions. In conclusion, Ramadan fasting had a small to moderate, negative impact on quality of performance during an acute high-intensity exercise session, particularly during the period of the daytime fast. The optimal time to conduct an acute high-intensity exercise session during the Ramadan fasting month is in the evening, after the breaking of the day's fast. (Author correspondence: abdul_rashid_aziz@ssc.gov.sg)     

High Intensity Exercise: A Cause of Lymphocyte Apoptosis?

Post exercise lymphocytopenia is well documented and attributed to egress of lymphocytes from the vascular compartment. Recent studies have reported exercise induced DNA damage in leukocytes and have questioned a possible link to apoptosis. Eleven subjects underwent a ramped treadmill test to exhaustion. Venous blood samples were taken before, immediately post exercise, and 24 and 48 hours after exercise. Single cell gel electrophoresis revealed evidence of single strand DNA damage in 10% of lymphocytes immediately after exercise, but not at other times. Fluorescent microscopy showed three patterns of DNA distribution, similar to those seen in apoptosis, at all times after exercise. Three subjects underwent the same exercise protocol, and lymphocytes were prepared for flow cytometry to determine apoptosis using the TUNEL method. Flow cytometry revealed lymphocyte apoptosis in 63% of lymphocytes immediately after exercise and 86.2%, 24 hours after exercise. Lymphocyte apoptosis is documented for the first time after exercise and may in part account for exercise induced lymphocytopenia and reduced immunity.     

How Do Humans Control Physiological Strain during Strenuous Endurance Exercise?

Background

Distance running performance is a viable model of human locomotion.

Methodology/Principal Findings

To evaluate the physiologic strain during competitions ranging from 5–100 km, we evaluated heart rate (HR) records of competitive runners (n = 211). We found evidence that: 1) physiologic strain (% of maximum HR (%HRmax)) increased in proportional manner relative to distance completed, and was regulated by variations in running pace; 2) the %HRmax achieved decreased with relative distance; 3) slower runners had similar %HRmax response within a racing distance compared to faster runners, and despite differences in pace, the profile of %HRmax during a race was very similar in runners of differing ability; and 4) in cases where there was a discontinuity in the running performance, there was evidence that physiologic effort was maintained for some time even after the pace had decreased.

Conclusions/Significance

The overall results suggest that athletes are actively regulating their relative physiologic strain during competition, although there is evidence of poor regulation in the case of competitive failures.     

Are the Eating and Exercise Habits of Successful Weight Losers Changing?

Objective : The purpose of this study was to examine whether the diet and exercise behaviors of successful weight losers entering the National Weight Control Registry (NWCR) have changed between 1995 and 2003. Research Method and Procedures : Participants (N = 2708) were members of the NWCR who enrolled in intermittent years since 1995. Participants had lost an average of 33.1 kg and maintained a 13.6‐kg loss for 5.8 years before enrollment. Evaluations of diet and physical activity were conducted at entry into the NWCR and prospectively over 1 year. Results : From 1995 to 2003, the daily percentage of calories from fat increased from 23.8% to 29.4%, saturated fat intake increased from 12.3 to 154.0 g/d, and calories from carbohydrate decreased from 56.0% to 49.3% (p < 0.0001). The proportion consuming <90 grams of carbohydrate (considered a low‐carbohydrate diet) increased from 5.9% to 17.1% (p = 0.0001). Physical activity was elevated in 1995 (mean = 3316 kcal/wk) but comparable in all other years (mean = 2620 kcal/wk). Stepwise regression collapsing across cohorts indicated that weight regain over 1 year was related to higher levels of caloric intake, fast food consumption, and fat intake and lower levels of physical activity (p < 0.03). Discussion : The macronutrient composition of the diet of NWCR members has shifted over the past decade. Still, only a minority consumes a low‐carbohydrate diet. Despite changes in the diet over time, the variables associated with long‐term maintenance of weight loss were the same: continued consumption of a low‐calorie diet with moderate fat intake, limited fast food, and high levels of physical activity.     

Exercise prevents leptin-induced increase in blood pressure in Sprague–Dawley rats

Although leptin has been shown to increase blood pressure (BP), it is however unclear if this increase can be prevented by exercise. This study therefore investigated the effect of leptin treatment with concurrent exercise on blood pressure (BP), sodium output, and endothelin-1 (ET-1) levels in normotensive rats. Male Sprague–Dawley rats weighing 250–270 g were divided into four groups consisting of a control group (n?=?6), leptin-treated (n?=?8), non-leptin-treated exercise group (n?=?8), and a leptin-treated exercise group (n?=?8). Leptin was given subcutaneously daily for 14 days (60 μg/kg/day). Animals were exercised on a treadmill for 30 min at a speed of 0.5 m/s and at 5° incline four times per week. Measurement of systolic blood pressure (SBP) and collection of urine samples for estimation of sodium and creatinine was done once a week. Serum samples were collected at the end of the experiment for determination of sodium, creatinine and ET-1. At day 14, mean SBP and serum ET-1 level in the leptin-treated group was significantly higher than that in the control group whereas mean SBP and serum ET-1 level was significantly lower in the leptin-treated exercise group than those in leptin-treated and control groups. Creatinine clearance, urinary sodium excretion, and urine output were not different between the four groups. Regular treadmill exercise prevents leptin-induced increases in SBP in rats, which might in part result from increased urinary sodium excretion and preventing the leptin-induced increases in serum ET-1 concentration.     

The Definition of “Applied Psychophysiology”: A Dangerous Exercise in Exclusivity

Dr. Schwartz's (1999) definition of applied psychophysiology and his attempt to limit what can be presented at the society's meeting, published in its journal, and by extension, used by members of AAPB, are discussed. The exclusivity is seen as repressive and even dangerous. Examples from irritable bowel syndrome and chronic headache are provided.     

Is cladogenesis heritable?

The heritability of speciation rates and extinction risks is a crucial parameter in models of macroevolution, but little direct evidence has been available to assess the occurrence, strength, or generality of this heritability. We tested for heritability using correlations between ancestral and descendent branch lengths in phylogenetic trees, an approach first applied to a bird phylogeny by Harvey et al. (1991, pages 123-137 in Genes in ecology [R. J. Berry et al., eds.], Blackwell Scientific, Oxford). We applied Harvey et al.'s test to some of the largest DNA sequence-based phylogenetic analyses published to date for plants, insects, fungi, and bacteria. If one of two parent lineages splits first and if this is the case for any heritable reason, then on average we expect its daughter lineages to also split first. We also used a randomization procedure to assess significance of branch length heritability. Using maximum parsimony and maximum likelihood branch lengths and trees made ultrametric after nonparametric rate smoothing or by enforcing a molecular clock, we found a pattern for most clades consistent with heritable net cladogenesis. Heritability of cladogenesis may be a general phenomenon, detectable across a large number of lineages and a broad range of taxa.     

Is mood chemistry?

The chemical hypothesis of depression suggests that mood disorders are caused by a chemical imbalance in the brain, which can be corrected by antidepressant drugs. However, recent evidence indicates that problems in information processing within neural networks, rather than changes in chemical balance, might underlie depression, and that antidepressant drugs induce plastic changes in neuronal connectivity, which gradually lead to improvements in neuronal information processing and recovery of mood.