Effects of a High Protein and Omega-3-Enriched Diet with or Without Creatine Supplementation on Markers of Soreness and Inflammation During 5 Consecutive Days of High Volume Resistance Exercise in Females.

We examined if two different dietary interventions affected markers of soreness and inflammation over a 5-day high-volume resistance training protocol in females that resistance-trained 8 weeks prior. Twenty-eight females (age: 20 ± 1 yr; body mass: 63.5 ± 1.6 kg, height: 1.67 ± 0.01 m) completed 4 weeks of pre-training (weeks 1-4) followed by a subsequent 4-week training period along with a dietary intervention (weeks 5-8). Dietary interventions from weeks 5-8 included: a) no intervention (CTL, n = 10) b) a higher-protein diet supplemented with hydrolyzed whey protein (50 g/d) and omega-3 fatty acids (900 mg/d) (DI, n = 8), and c) the DI condition as well as creatine monohydrate (5 g/d) (DI+C, n = 10). During week 9, participants resistance-trained for five consecutive days whereby 8 sets of 10 target repetitions at 70% one repetition maximum (1RM) were performed each day for bench press, back squat, deadlift, and hip-thrusters with the intent of eliciting muscle soreness and inflammation. Prior to and 24 h following each of the 5 bouts muscle soreness (DOMS) was assessed via questionnaire, and fasting blood was obtained and analyzed for serum cortisol, interleukin-6 (IL-6) and C-reactive protein (CRP). No group*time (G*T) or time effects were observed for training volume over the 5-d overreaching protocol. Furthermore, no group*time (G*T) or time effects were observed for serum cortisol, IL-6 or CRP, and DOMS actually decreased in all groups 24 h following the fifth day training bout. This study demonstrates that, regardless of protein, omega-3 fatty acid and/or creatine supplementation, 5 days of consecutive resistance training does not alter perceived muscle soreness, training volume, and/or markers of inflammation in novice resistance-trained females. Key points We examined if two different dietary interventions (higher protein and omega-3 supplementation, or higher protein and omega-3 supplementation with creatine supplementation) affected muscle soreness and inflammation markers over a 5-day high-volume resistance training protocol in females that resistance-trained 8 weeks prior. Neither dietary intervention affected training volume, muscle soreness and inflammation markers over the 5-d consecutive training period. More research is needed in order to determine if the dietary interventions employed herein affects athletes which may experience overreaching-like symptoms over a training season. Key words: Whey protein, creatine monohydrate, muscle soreness, inflammation Introduction Overreaching is posited to occur with high-volume and high-frequency resistance or endurance training with inadequate recovery. Resistance exercise-induced overreaching or overtraining has been theorized to potentially disrupt hormonal status (i.e., reduce testosterone and insulin-like levels and increase cortisol and catecholamine levels), reduce strength and power, and result in increased levels of inflammation (Fry and Kraemer, 1997; Fry et al., 1994; 1998; 2006; Goto et al., 2013; Steinacker et al., 2004). One prevailing issue in overreaching and overtraining research is the putative lack of laboratory-based resistance training protocols which promote an ‘overreaching’-like signature as discussed above. In this regard, some researchers have questioned if overreaching or overtraining is a true physiological phenomena (Halson and Jeukendrup, 2004). Notwithstanding, putative resistance-training induced overreaching protocols include: a) one-day eccentric resistance exercise protocols which lead to appreciable increases in markers of muscle damage and inflammation as well as significant decrements in force or power production (Howatson et al., 2012; Kerksick et al., 2013), b) consecutive three-day bouts of eccentric resistance training which, like one-day eccentric training protocols, lead to the aforementioned decrements in performance and increases in inflammation (Willoughby et al., 2003), or c) 4-6 weeks of higher-volume/frequency heavy resistance exercise training (Ratamess et al., 2003; Volek et al., 2004). Indeed, while these laboratory-based protocols are not characteristic of long-term overreaching or overtraining that may be observed in athletes, these ‘accelerated’ protocols lead to acute changes in muscle damage and inflammation biomarkers which may be observed with chronic overtraining. A prevailing hypothesis is that nutritional factors can mitigate indices of resistance exercise-induced overreaching and, in this regard, several studies have examined the effects of amino acid supplementation on markers of overreaching. For instance, an investigation by Ratamess and colleagues (2003) determined that essential (EAA) supplementation during 4 weeks of high-volume resistance training reduced rate of fatigue during a post-intervention 20-repetition jump squat test. Howatson et al. (2012) also reported that short-term branched chain amino acid (BCAA) supplementation was better able to preserve muscle strength following a short-term muscle damage protocol. Thus, there is evidence to also suggest that amino acid supplementation can attenuate the effects of resistance training-induced overreaching in a laboratory setting, and this may be related to either an enhancement in post-exercise anabolic processes in skeletal muscle (Campbell et al., 2007; Tipton et al., 1999) and/or alterations in circulating BCAA: tryptophan ratios which prevents excessive serotonin production and reduces the potential ‘central’ fatigue that can accompany overreaching (Blomstrand, 2001). Beyond the potential beneficial effects that amino acid supplementation (or higher protein diets) may exert on overreaching-like symptoms, other nutritional modulators may mitigate overreaching. For instance, it stands to reason that creatine supplementation may mitigate overreaching given that vast research evidence has shown creatine supplementation to be beneficial for increasing strength and power (Buford et al., 2007; Kreider et al., 2010; Terjung et al., 2000). Furthermore, a study by Volek et al. (2004) reported that creatine supplementation prevented power and strength losses over a 6-week overreaching protocol. Omega-3 fatty acid supplementation also carries promise in preventing overreaching given that supplementation has been shown to reduce post-exercise muscle inflammation (Bloomer et al., 2009; Corder et al., 2016). Specifically, it has been posited that chronic omega-3 fatty acid supplementation displaces omega-6 fatty acid content in muscle cell membrane structures which, in turn, reduces the pro-inflammatory prostaglandin response to exercise (Lenn et al., 2002). Notwithstanding, beyond investigations which have reported that omega-3 fatty acid supplementation reduces the acute post-exercise inflammatory response, no studies to our knowledge have examined if chronic supplementation improves recovery during laboratory-based high-volume consecutive-day resistance training protocols. Therefore, the primary purpose of this investigation was to examine if two different dietary interventions prevented increases in muscle soreness and/or serum inflammation markers in females over a 5-day high volume resistance training protocol. These dietary interventions included: a) a higher-protein diet supplemented with omega-3 fatty acids, and b) a higher-protein diet supplemented with omega-3 fatty acids as well as creatine monohydrate. Notably, the intent of the 5-day consecutive training protocol was to elicit an accelerated overreaching response. We hypothesized that both diets would reduce the aforementioned markers during the 5-day protocol compared to control participants, and further hypothesized that the creatine-supplemented group would have the most optimal response during the week 9 training period (i.e., the least soreness and sustainment of lifting volume, lowered inflammatory markers).