Oral sodium lactate ingestion does not increase blood lactate concentrations and is accompanied by moderate to severe gastrointestinal side effects.

Lactate has diverse roles in biology and has been implicated in the control of energy intake. A variety of methods (i.e., exercise, ingestion, infusion) have been used to study its effects on different metabolic outcomes and the original intent of this project was to explore the effect of oral sodium lactate (Na-Lactate) ingestion on appetite regulation. During piloting we were unable to show that Na-Lactate could increase blood lactate concentrations, thus the purpose of the brief manuscript is to highlight that oral Na-Lactate ingestion is not an effective method to study lactate metabolism. Five male participants (26 ± 3 y, 82.4 ± 3.8 kg, 25.4 ± 1.6 kg∙m-2) completed 15 experimental sessions where Na-Lactate solutions were consumed with assessment of blood lactate pre-ingestion, 30 min, 45 min, and 60 min post-ingestion. Oral Na-Lactate ingestion did not increase blood lactate concentrations (Pre: 0.9±0.2; 30 min: 1.2±0.7; 45 min: 1.0±0.5; 60 min: 0.9±0.4 mmol∙L-1). Additionally, there were moderate-severe gastrointestinal (GI) side effects (e.g., vomiting, diarrhea) following ingestion. Taken together our data suggest that oral ingestion of Na-Lactate is not an effective method to study lactate's role on metabolism as it did not increase blood lactate concentrations and was accompanied by problematic GI side effects.

The Effect of the Menstrual Cycle on Energy Intake: A Systematic Review and Meta-analysis.

CONTEXT: Energy intake may differ across the menstrual cycle, with some studies identifying greater energy intake in the luteal phase (LP) compared with the follicular phase (FP) and others finding no clear differences. To date, no study has systematically synthesized the available data to draw more definite conclusions while considering any methodological inconsistencies between studies. OBJECTIVE: The aim was to conduct a systematic review/meta-analysis in an effort to determine if there are differences in energy intake between the FP and LP. DATA SOURCES: A systematic search strategy was developed and the search was conducted in 5 databases for studies that investigated any changes in energy intake across menstrual phases. DATA EXTRACTION: Using Covidence, studies were identified and included if they contained individuals between the ages of 18 and 45 years, maintained an average body mass index (BMI) of 18.5-25 kg/m2, had no history of disordered eating, and included energy intake and menstrual cycle measurements in the FP and LP. DATA ANALYSIS: Effect sizes were calculated for each study and a random-effects model was used to pool the results of each study. RESULTS: Fifteen datasets were included consisting of 330 female participants with a mean age of 26 ± 4 years and mean BMI of 22.4 ± 2.3 kg/m2. Overall, there was a statistically significant difference (standardized mean difference = 0.69; P = .039) with increased energy intake in the LP compared with the FP (crude 168 kcal⋅d-1 average difference between phases). CONCLUSION: Energy intake was found to be greater in the LP compared with the FP, providing insight into the effect of the menstrual cycle on energy intake. However, there were repeated methodological inconsistencies and future work should strive to utilize best practices for both energy intake measurement and menstrual phase specification.

Low-Load and High-Load Resistance Exercise Completed to Volitional Fatigue Induce Increases in Postexercise Metabolic Responses With More Prolonged Responses With the Low-Load Protocol.

ABSTRACT: Grisebach, D, Bornath, DPD, McCarthy, SF, Jarosz, C, and Hazell, TJ. Low-load and high-load resistance exercise completed to volitional fatigue induce increases in post-exercise metabolic responses with more prolonged responses with the low-load protocol. J Strength Cond Res 38(8): 1386-1393, 2024-Comparisons of high-load with low-load resistance training (RT) exercise have demonstrated no differences in postexercise metabolism when volume is matched. This important limitation of matching or equating volume diminishes benefits of the low-load RT protocol. Therefore, the purpose of this study was to determine the effects of acute low-load high volume and high-load low volume RT protocols completed to volitional fatigue on postexercise metabolism. Eleven recreationally active resistance-trained male subjects (24 ± 2 years; BMI: 25.3 ± 1.5 kg·m -2 ) completed 3 experimental sessions: (a) no-exercise control (CTRL); (b) RT at 30% 1 repetition maximum (1RM; 30% 1RM); and (c) RT at 90% 1RM (90% 1RM) with oxygen consumption (V̇ o2 ) measurements 2 hours postexercise. The RT sessions consisted of 3 sets of back squats, bench press, straight-leg deadlift, military press, and bent-over rows to volitional fatigue completed sequentially with 90 seconds of rest between sets and exercises. Changes were considered important if p < 0.100 with a ≥medium effect size. V̇ o2 1 hour postexercise was elevated following 30% 1RM (25%; p = 0.003, d = 1.40) and 90% 1RM (14%; p = 0.010, d = 1.15) vs. CTRL and remained elevated 2 hours postexercise following 30% 1RM (16%; p = 0.010, d = 1.15) vs. CTRL. Total O 2 consumed postexercise increased following 30% 1RM and 90% 1RM (∼17%; p < 0.044, d > 0.91) vs. CTRL. Fat oxidation was elevated 1 hour postexercise following 30% 1RM and 90% 1RM (∼155%; p < 0.001, d > 2.97) and remained elevated 2 hours postexercise following 30% 1RM compared with CTRL and 90% 1RM (∼69%; p < 0.030, d > 1.03). These data demonstrate beneficial changes to postexercise metabolism following high- and low-load RT sessions, with more prolonged effects following the low-load RT protocol completed to volitional fatigue.

Differential changes in appetite hormones post-prandially based on menstrual cycle phase and oral contraceptive use: A preliminary study.

This was a preliminary study that examined whether appetite regulation is altered during the menstrual cycle or with oral contraceptives. Ten naturally cycling females (NON-USERS) and nine tri-phasic oral contraceptive using females (USERS) completed experimental sessions during each menstrual phase (follicular phase: FP; ovulatory phase: OP; luteal phase: LP). Appetite perceptions and blood samples were obtained fasted, 30, 60, and 90 min post-prandial to measure acylated ghrelin, active glucagon-like peptide-1 (GLP-1), and total peptide tyrosine tyrosine (PYY). Changes were considered important if p < 0.100 and the effect size was ≥medium. There appeared to be a three-way (group x phase x time) interaction for acylated ghrelin where concentrations appeared to be greater in USERS versus NON-USERS during the OP 90-min post-prandial and during the LP fasted, and 90-min post-prandial. In USERS, ghrelin appeared to be greater 90-min post-prandial in the OP versus the FP with no other apparent differences between phases. There were no apparent differences between phases in NON-USERS. There appeared to be a three-way interaction for PYY where concentrations appeared to be greater in USERS during the FP 60-min post-prandial and during the OP 30-min post-prandial. In USERS PYY appeared to be greater 60-min post-prandial during the OP versus the LP with no other apparent differences. There were no apparent differences between phases in NON-USERS. There appeared to be no effect of group or phase on GLP-1, or appetite perceptions. These data demonstrate small effects of menstrual cycle phase and oral contraceptive use on the acylated ghrelin and total PYY response to a standardized meal, with no effects on active GLP-1 or perceived appetite, though more work with a large sample size is necessary.

Low- and high-load resistance training exercise to volitional fatigue generate exercise-induced appetite suppression.

Research on exercise-induced appetite suppression often does not include resistance training (RT) exercise and only compared matched volumes. PURPOSE: To compare the effects of low-load and high-load RT exercise completed to volitional fatigue on appetite-regulation. METHODS: 11 resistance-trained males (24 ± 2 y) completed 3 sessions in a crossover experimental design: 1) control (CTRL); 2) RT exercise at 30% 1-repetition maximum (RM); and 3) RT exercise at 90% 1-RM. RT sessions consisted of 3 sets of 5 exercises completed to volitional fatigue. Acylated ghrelin, active glucagon-like peptide-1 (GLP-1), active peptide tyrosine (PYY), lactate, and subjective appetite perceptions were measured pre-exercise, 0-, 60-, and 120-min post-exercise. Energy intake was recorded the day before, of, and after each session. RESULTS: Lactate was elevated following both 30% (0-, 60-, 120-min post-exercise) and 90% (0-, 60-min post-exercise; P < 0.001, d > 3.92) versus CTRL, with 30% greater than 90% (0-min post-exercise; P = 0.011, d = 1.14). Acylated ghrelin was suppressed by 30% (P < 0.007, d > 1.22) and 90% (P < 0.028, d > 0.096) post-exercise versus CTRL, and 30% suppressed concentrations versus 90% (60-min post-exercise; P = 0.032, d = 0.95). There was no effect on PYY (P > 0.171, ηp2 <0.149) though GLP-1 was greater at 60-min post-exercise in 90% (P = 0.052, d = 0.86) versus CTRL. Overall appetite was suppressed 0-min post-exercise following 30% and 90% versus CTRL (P < 0.013, d > 1.10) with no other differences (P > 0.279, d < 0.56). There were no differences in energy intake (P > 0.101, ηp2 <0.319). CONCLUSIONS: RT at low- and high-loads to volitional fatigue induced appetite suppression coinciding with changes in acylated ghrelin though limited effects on anorexigenic hormones or free-living energy intake were present.

Leptin and energy balance: exploring Leptin's role in the regulation of energy intake and energy expenditure.

Leptin is a tonic appetite-regulating hormone, which is integral for the long-term regulation of energy balance. The current evidence suggests that the typical orexigenic or anorexigenic response of many of these appetite-regulating hormones, most notably ghrelin and cholecystokinin (CCK), require leptin to function whereas glucagon-like peptide-1 (GLP-1) is required for leptin to function, and these responses are altered when leptin injection or gene therapy is administered in combination with these same hormones or respective agonists. The appetite-regulatory pathway is complex, thus peptide tyrosine tyrosine (PYY), brain-derived neurotrophic factor (BDNF), orexin-A (OXA), and amylin also maintain ties to leptin, however these are less well understood. While reviews to date have focused on the existing relationships between leptin and the various neuropeptide modulators of appetite within the central nervous system (CNS) or it's role in thermogenesis, no review paper has synthesised the information regarding the interactions between appetite-regulating hormones and how leptin as a chronic regulator of energy balance can influence the acute appetite-regulatory response. Current evidence suggests that potential relationships exist between leptin and the circulating peripheral appetite hormones ghrelin, GLP-1, CCK, OXA and amylin to exhibit either synergistic or opposing effects on appetite inhibition. Though more research is warranted, leptin appears to be integral in both energy intake and energy expenditure. More specifically, functional leptin receptors appear to play an essential role in these processes.

Interleukin-6 is not involved in appetite regulation following moderate-intensity exercise in males with normal weight and obesity.

OBJECTIVE: In obesogenic states and after exercise, interleukin (IL)-6 elevations are established, and IL-6 is speculated to be an appetite-regulating mechanism. This study examined the role of IL-6 on exercise-induced appetite regulation in sedentary normal weight (NW) males and those with obesity (OB). METHODS: Nine NW participants and eight participants with OB completed one non-exercise control (CTRL) and one moderate-intensity continuous training (MICT; 60 minutes, 65% V̇O2max ) session. IL-6, acylated ghrelin, active peptide tyrosine-tyrosine3-36 , active glucagon-like peptide-1, and overall appetite perceptions were measured fasted, pre exercise, and 30, 90, and 150 minutes post exercise. RESULTS: Fasted IL-6 concentrations were elevated in OB (p = 0.005, η p 2 = 0.419); however, increases following exercise were similar between groups (p = 0.934, η p 2 = 0.000). Acylated ghrelin was lower in OB versus NW (p < 0.017, d > 0.84), and OB did not respond to MICT (p > 0.512, d < 0.44) although NW had a decrease versus CTRL (p < 0.034, d > 0.61). IL-6 did not moderate/mediate acylated ghrelin release after exercise (p > 0.251). There were no observable effects of MICT on tyrosine-tyrosine3-36 , glucagon-like peptide-1, or overall appetite (p > 0.334, η p 2 < 0.062). CONCLUSIONS: These results suggest that IL-6 is not involved in exercise-induced appetite suppression. Despite blunted appetite-regulatory peptide responses to MICT in participants with OB, NW participants exhibited decreased acylated ghrelin; however, no differences in appetite perceptions existed between CTRL and MICT or NW and OB.

Intense interval exercise induces lactate accumulation and a greater suppression of acylated ghrelin compared with submaximal exercise in middle-aged adults.

Exercise in young adults (18-25 yr) suppresses appetite in a dose-response relationship with exercise intensity. Although several mechanisms have been proposed to explain this response, lactate is the most well established. To date, no study has investigated this specifically in middle-aged adults where the appetite response to a meal is different. To explore the effects of submaximal, near maximal, and supramaximal intensity exercise on appetite regulation in middle-aged adults. Nine participants (age: 45 ± 10 yr) completed four experimental sessions: 1) no-exercise control (CTRL); 2) moderate-intensity continuous training [MICT; 30 min, 65% maximal oxygen consumption (V̇o2max)]; 3) high-intensity interval training (HIIT; 10 × 1 min efforts, 90% heart rate maximum, 1 min recovery); and 4) sprint interval training (SIT; 8 × 15 s "all-out" efforts, 2 min recovery). Acylated ghrelin, active glucagon-like peptide-1 (GLP-1), active peptide tyrosine tyrosine (PYY), lactate, and subjective appetite perceptions were measured pre-exercise, 0-, 30-, and 90-min postexercise. Energy intake was recorded the day before and day of each session. Acylated ghrelin was suppressed (P < 0.001, [Formula: see text] = 0.474) by HIIT (0-min and 30-min postexercise; P < 0.091, d > 1.84) and SIT (0-min, 30-min, and 90-min postexercise; P < 0.037, d > 1.72) compared with CTRL, and SIT suppressed concentrations compared with MICT (0-min and 30-min postexercise; P < 0.91, d > 1.19). There were no effects of exercise on active PYY, active GLP-1, appetite perceptions, or free-living energy intake (P > 0.126, [Formula: see text] < 0.200). Intense interval exercise that generates lactate accumulation suppresses acylated ghrelin with little effect on anorexigenic hormones, overall appetite, or free-living energy intake.NEW & NOTEWORTHY We explored the effects of submaximal, near maximal, and supramaximal intensity exercise on appetite regulation in middle-aged adults. Our data support the intensity-dependent effect of exercise on acylated ghrelin suppression that is closely related to lactate accumulation, though there appears to be little effect on anorexigenic hormones [active peptide tyrosine tyrosine (PYY), active glucagon-like peptide-1 (GLP-1)], overall appetite, or free-living energy intake. These data support previous results in younger adults where lactate was implicated in the exercise-induced suppression of acylated ghrelin.

Classroom Activity Breaks Improve On-Task Behavior and Physical Activity Levels Regardless of Time of Day.

Classroom physical activity breaks (CAB) are beneficial for increasing children's physical activity (PA) levels as well as the amount of time spent being on-task within the classroom. Purpose: To examine the effect of CAB at different times within the school day on on-task behavior and PA levels in primary school (grade 1-3) children. Methods: Thirty-five children (6 ± 1 y, 22 = male, 13 = female) participated in four conditions in a randomized order: morning (AM), afternoon (PM), morning and afternoon (BOTH), and no CAB (CTRL). CAB followed a traditional Tabata format of 20 s work and 10 s rest repeated 8 times for a total of 4 min. PA levels were monitored (accelerometry). On-task behavior and three types of off-task (motor, verbal, passive) were recorded following each CAB (mobile application). Results: When compared to control, AM, PM, and BOTH increased on-task behavior AM: Δ10.4%, PM: Δ10.5%, BOTH: Δ14%; p < .001). AM was most beneficial for reducing off-task motor (Δ-6.5%) and off-task verbal (Δ-3%) behavior, while PM was most beneficial for reducing off-task passive (Δ-9%) behavior. These effects were greatest in those students demonstrating higher amounts off-task behavior during CTRL (r > 0.67, p < .001). Students achieved an additional 8.4 (p = .070; d = 0.93), 12.2 (p < .001, d = 0.49), and 6.3 min (p = .09, d = 0.47) of moderate-vigorous physical activity (MVPA) over 24 h following a CAB vs CTRL in AM, PM, and BOTH, respectively. Additionally, performing any of the CAB conditions increased the number of steps taken during the school day by an average of 2007 steps (p < .009). Conclusion: Overall, these results demonstrate that CAB improve both on-task behavior and PA levels, regardless of time of day. However, performing two CAB (BOTH) is recommended to derive the greatest improvements in on-task behavior across the school day.

Physiological Responses to Increasing Battling Rope Weight During Two 3-Week High-Intensity Interval Training Programs.

ABSTRACT: Bornath, DPD and Kenno, KA. Physiological responses to increasing battling rope weight during two 3-week high-intensity interval training programs. J Strength Cond Res 36(2): 352-358, 2022-The purpose of this study was to determine the effect of increasing battling rope weight during 6 weeks (wks) of battling rope high-intensity interval training (HIIT) on upper-body oxygen consumption and skeletal muscle strength, power, and endurance performance. Eighteen recreationally active men and 15 women (23 ± 2 year) performed 10 × 30-second (s) bouts of all-out exercise, interchanging between double and alternating whip battling rope exercises, separated by 60 seconds of rest, 3×/wk, for 6 weeks. For the first 3 weeks, women used 40-foot, 1.5-inch diameter, 20-lb ropes and men used 50-foot, 1.5-inch diameter, 25-lb ropes, after which the battling rope weight was increased by 10 lb for a second 3-week period of battling rope HIIT. Men and women exercised at a minimum of 85% of their predicted maximum heart rate with post-exercise blood lactate concentrations peaking at 10.79 mmol·L-1 and 8.33 mmol·L-1, respectively. After 3 and 6 weeks of battling rope HIIT, men and women increased upper-body maximal oxygen consumption (V̇o2max), maximum voluntary contraction isometric shoulder flexion and extension strength, shoulder power output, and push-up and sit-up endurance. These increases in aerobic and skeletal muscle measurements are similar to previous HIIT studies involving treadmills and cycle ergometers. Battling rope HIIT produced adaptations in skeletal muscle and aerobic performance in as little as 3 weeks, and with increases in battling rope weight displayed further improvements after 6 weeks of battling rope HIIT. These data support the implementation of battling rope HIIT to improve cardiorespiratory fitness and skeletal muscle performance with increased workloads.