title: The effect of carbohydrate and protein co-ingestion on energy substrate metabolism, sense of effort, and affective responses during prolonged strenuous endurance exercise.
abstract: This study examined the effect of carbohydrate (CHO) and protein (PRO) co-ingestion on energy substrate metabolism, sense of effort, and affective responses during prolonged strenuous endurance exercise. In a four-stage randomized cross-over design, 10 male endurance runners (age: 27.3±1.4yrs; height: 172.9±1.1cm, weight: 63.5±1.6kg; body fat: 9.0±1.4%; V̇O2max: 62.9±1.8ml/kg/min) ran on a treadmill at 70% of their individual V̇O2maxfor 90min. There were two CHO and PRO treatments (CA: CHO+alpha-lactalbumin and CW: CHO+whey PRO isolate), one CHO treatment (CC: CHO+CHO), and a placebo control (CON). On each occasion, subjects consumed 5ml/kg according to their body weight (kg) immediately before and 2ml/kg every 15min during exercise. Blood samples were collected at 0min, 30min, 60min and 90min of exercise to measure glucose, lactate, insulin, and cortisol levels. The extent of physical sensation (abdominal discomfort, leg muscle pain), the sense of effort (rating of perceive exertion, RPE), and affective responses (pleasure-displeasure, arousal) were evaluated by numeric scales before, during, and immediately after exercise. Blood glucose and insulin concentrations in the CA, CW, and CC treatments were higher than in the CON at 90min (P<0.05). Muscle pain (evaluated by a single item, 0 to 10 pain intensity scale from "no pain at all" to "extremely unbearable") was lower following CA ingestion than CON and CW ingestion, at 75min (vs. CON and CW, 1.95±0.61 vs. 3.70±1.00 and 3.60±1.02, P<0.05) and 90min (vs.
  
  
  
  2.40±0.76 vs. 4.20±0.99 and 4.05±1.1, P<0.05). RPE (evaluated by a 15-point, 6 to 20 rating scale ranging from "very, very light" to "very, very hard") following treatment with CA was lower than with CON and CW at 90min (vs. CON and CW: 11.30±1.14 vs. 14.20±1.30 and 13.30±1.24, P<0.05). Compared with CON and CW, CA enhanced the feeling of pleasure (evaluated by feeling scale from -5, "very bad" to +5, "very good") at 90min (vs. CON and CW, 2.20±0.67 vs. -0.30±0.94 and 0.20±0.91, P<0.05). Co-ingestion of CHO and alpha-lactalbumin protein attenuates muscle pain, and therefore alleviates the sense of effort and enhances affective responses during 90min of strenuous running at 70% V̇O2max.
authors.affiliation: Department of Sports Science and Physical Education, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: L
authors.initials: L
authors.lastname: Qin
authors.affiliation: Department of Sports Science and Physical Education, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong. Electronic address: hsswong@cuhk.edu.hk.
authors.forename: S H
authors.initials: SH
authors.lastname: Wong
authors.affiliation: Department of Health and Physical Education, The Education University of Hong Kong, Tai Po, Hong Kong.
authors.forename: F-H
authors.initials: FH
authors.lastname: Sun
authors.affiliation: School of Biomedical Sciences and Institute of Vascular Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong.
authors.forename: Y
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Department of Sports Science and Physical Education, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: S
authors.initials: S
authors.lastname: Sheridan
authors.affiliation: Department of Sports Science and Physical Education, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: C H P
authors.initials: CHP
authors.lastname: Sit
mesh_terms: D015746:Abdominal Pain / Q000209:etiology; D000293:Adolescent; D000328:Adult; D000339:Affect / Q000187:drug effects*; D001786:Blood Glucose / Q000187:drug effects; D002241:Carbohydrates / Q000494:pharmacology*; D004734:Energy Metabolism / Q000187:drug effects*; D064368:Healthy Volunteers; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008297:Male; D063806:Myalgia / Q000209:etiology; D010101:Oxygen Consumption / Q000187:drug effects*; D010807:Physical Endurance / Q000187:drug effects / Q000502:physiology*; D011506:Proteins / Q000494:pharmacology*; D013997:Time Factors; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D002241:Carbohydrates; D007328:Insulin; D011506:Proteins; D019344:Lactic Acid; D006854:Hydrocortisone
keywords: Metabolism; Nutrition; Perceived exertion; Pleasure-displeasure; Running