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Partly Substituting Whey for Collagen Peptide Supplementation Improves Neither Indices of Muscle Damage Nor Recovery of Functional Capacity During Eccentric Exercise Training in Fit Males

Ruben Robberechts, Chiel Poffé, Noémie Ampe, Stijn Bogaerts, and Peter Hespel

Previous studies showed that collagen peptide supplementation along with resistance exercise enhance muscular recovery and function. Yet, the efficacy of collagen peptide supplementation in addition to standard nutritional practices in athletes remains unclear. Therefore, the objective of the study was to compare the effects of combined collagen peptide (20 g) and whey protein (25 g) supplementation with a similar daily protein dose (45 g) of whey protein alone on indices of muscle damage and recovery of muscular performance during eccentric exercise training. Young fit males participated in a 3-week training period involving unilateral eccentric exercises for the knee extensors. According to a double-blind, randomized, parallel-group design, before and after training, they received either whey protein (n = 11) or whey protein + collagen peptides (n = 11). Forty-eight hours after the first training session, maximal voluntary isometric and dynamic contraction of the knee extensors were transiently impaired by ∼10% (P time < .001) in whey protein and whey protein + collagen peptides, while creatine kinase levels were doubled in both groups (P time < .01). Furthermore, the training intervention improved countermovement jump performance and maximal voluntary dynamic contraction by respectively 8% and 10% (P time < .01) and increased serum procollagen type 1N-terminal peptide concentration by 10% (P time < .01). However, no differences were found for any of the outcomes between whey and whey protein + collagen peptides. In conclusion, substituting a portion of whey protein for collagen peptide, within a similar total protein dose, improved neither indices of eccentric muscle damage nor functional outcomes during eccentric training.

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Acute Rhodiola Rosea Intake Can Improve Endurance Exercise Performance

Katrien De Bock, Bert O. Eijnde, Monique Ramaekers, and Peter Hespel


The purpose of this study was to investigate the effect of acute and 4-week Rhodiola rosea intake on physical capacity, muscle strength, speed of limb movement, reaction time, and attention.


PHASE I: A double blind placebo-controlled randomized study (n = 24) was performed, consisting of 2 sessions (2 days per session). Day 1: One hour after acute Rhodiola rosea intake (R, 200-mg Rhodiola rosea extract containing 3% rosavin + 1% salidroside plus 500 mg starch) or placebo (P, 700 mg starch) speed of limb movement (plate tapping test), aural and visual reaction time, and the ability to sustain attention (Fepsy Vigilance test) were assessed. Day 2: Following the same intake procedure as on day 1, maximal isometric knee-extension torque and endurance exercise capacity were tested. Following a 5-day washout period, the experimental procedure was repeated, with the treatment regimens being switched between groups (session 2). PHASE II: A double blind placebo-controlled study (n = 12) was performed. Subjects underwent sessions 3 and 4, identical to Phase I, separated by a 4-week R/P intake, during which subjects ingested 200 mg R/P per day.


PHASE I: Compared with P, acute R intake in Phase I increased 0 < -05) time to exhaustion from 16.8 ± 0.7 min to 17.2 ± 0.8 min. Accordingly, VO2peak (p < .05) and VCO2peak(p< .05) increased during R compared to P from 50.9 ± 1.8 ml • min-1 • kg−1 to 52.9 ± 2.7 ml • min-1 • kg"’ (VO2peak) and from 60.0 ± 2.3 ml • min-1 • kg-’ to 63.5 ± 2.7 ml • min-1 kg-1 (VCO2peak). Pulmonary ventilation (p = .07) tended to increase more during R than during P(P: 115.9±7.7L/min; R: 124.8 ± 7.7 L/min). All other parameters remained unchanged. PHASE II: Four-week R intake did not alter any of the variables measured.


Acute Rhodiola rosea intake can improve endurance exercise capacity in young healthy volunteers. This response was not altered by prior daily 4-week Rhodiola intake.

Restricted access

Opuntia Ficus-Indica Ingestion Stimulates Peripheral Disposal of Oral Glucose Before and After Exercise in Healthy Men

Karen Van Proeyen, Monique Ramaekers, Ivo Pischel, and Peter Hespel

The purpose of this study was to investigate the effect of Opuntia ficus-indica (OFI) cladode and fruit-skin extract on blood glucose and plasma insulin increments due to high-dose carbohydrate ingestion, before and after exercise. Healthy, physically active men (n = 6; 21.0 ± 1.6 years, 78.1 ± 6.0 kg) participated in a doubleblind placebo-controlled crossover study involving 2 experimental sessions. In each session, the subjects successively underwent an oral glucose tolerance test at rest (OGTTR), a 30-min cycling bout at ~75% VO2max, and another OGTT after exercise (OGTTEX). They received capsules containing either 1,000 mg OFI or placebo (PL) 30 min before and immediately after the OGTTR. Blood samples were collected before (t 0) and at 30-min intervals after ingestion of 75 g glucose for determination of blood glucose and serum insulin. In OGTTEX an additional 75-g oral glucose bolus was administered at t 60. In OGTTR, OFI administration reduced the area under the glucose curve (AUCGLUC) by 26%, mainly due to lower blood glucose levels at t 30 and t 60 (p < .05). Furthermore, a higher serum insulin concentration was noted after OFI intake at baseline and at t 30 (p < .05). In OGTTEX, blood glucose at t 60 was ~10% lower in OFI than in PL, which resulted in a decreased AUCGLUC (–37%, p < .05). However, insulin values and AUCINS were not different between OFI and PL. In conclusion, the current study shows that OFI extract can increase plasma insulin and thereby facilitate the clearance of an oral glucose load from the circulation at rest and after endurance exercise in healthy men.

Open access

Semiautomatic Training Load Determination in Endurance Athletes

Christophe Dausin, Sergio Ruiz-Carmona, Ruben De Bosscher, Kristel Janssens, Lieven Herbots, Hein Heidbuchel, Peter Hespel, Véronique Cornelissen, Rik Willems, André La Gerche, Guido Claessen, and on behalf of the Pro@Heart Consortium*

Background: Despite endurance athletes recording their training data electronically, researchers in sports cardiology rely on questionnaires to quantify training load. This is due to the complexity of quantifying large numbers of training files. We aimed to develop a semiautomatic postprocessing tool to quantify training load in clinical studies. Methods: Training data were collected from two prospective athlete’s heart studies (Master Athlete’s Heart study and Prospective Athlete Heart study). Using in-house developed software, maximal heart rate (MaxHR) and training load were calculated from heart rate monitored during cumulative training sessions. The MaxHR in the lab was compared with the MaxHR in the field. Lucia training impulse score, based on individually based exercise intensity zones, and Edwards training impulse, based on MaxHR in the field, were compared. A questionnaire was used to determine the number of training sessions and training hours per week. Results: Forty-three athletes recorded their training sessions using a chest-worn heart rate monitor and were selected for this analysis. MaxHR in the lab was significantly lower compared with MaxHR in the field (183 ± 12 bpm vs. 188 ± 13 bpm, p < .01), but correlated strongly (r = .81, p < .01) with acceptable limits of agreement (±15.4 bpm). An excellent correlation was found between Lucia training impulse score and Edwards training impulse (r = .92, p < .0001). The quantified number of training sessions and training hours did not correlate with the number of training sessions (r = .20) and training hours (r = −.12) reported by questionnaires. Conclusion: Semiautomatic measurement of training load is feasible in a wide age group. Standard exercise questionnaires are insufficiently accurate in comparison to objective training load quantification.