Biomedical subjects

Alejandro F San Juan

Publications and source records attributed to Alejandro F San Juan.

10 recordsLinked to original sources

PubMed2026

Could creatine supplementation combined with physical rehabilitation accelerate return to play in athletes with patellar tendinopathy?

BACKGROUND: Several dietary supplements have been proposed to positively influence the rehabilitation process following injury. However, to date, no studies have specifically examined the effects of scientifically supported ergogenic aids on recovery outcomes when combined with physical performance interventions. Therefore, the aim of this study was to analyze the ergogenic effects of creatine supplementation on neuromuscular performance, tendon thickness, pain, and body composition in athletes diagnosed with patellar tendinopathy (PT). METHODS: Using a triple-blind experimental design, 20 federated athletes (age: 33.7 ± 9.84 years) with PT were randomly assigned to either a creatine supplementation group (CR; n = 9) or a placebo group (PLA; n = 11). All participants followed a physical rehabilitation intervention that included daily eccentric training combined with stretching exercises, along with one session every 10 days of extracorporeal shock wave therapy (ESWT) and manual therapy targeting the tendon and surrounding muscle tissue. At the end of each eccentric training session, the participants ingested 3 capsules of creatine monohydrate - Creapure® (CR) or sucrose (PLA). At the beginning (PRE), after 4 weeks (MID), and after 8 weeks (POST), the pain level (Victorian Institute for Sports Assessment-Patella, VISA-P), tendon thickness (echography), body composition (bioelectrical impedance system), and neuromuscular performance using a countermovement jump test (CMJ) and a strength test (5-RM) of knee extension in the injured leg. RESULTS: A significant main effect of time was observed for VISA-P scores (p < 0.001; η2 p = 0.626), indicating a reduction in pain over time in both the creatine (CR) and placebo (PLA) groups. At POST, both groups showed significant improvements compared to PRE (CR: 78.0 points [69.2-86.8] vs. 60.6 points [53.4-67.7]; p = 0.002; PLA: 75.2 points [66.3-84.0] vs. 60.0 points [52.5-67.5]; p = 0.003). However, only the CR group showed a statistically significant improvement in the MID compared to PRE (MID: 70.2 points [60.0-80.5]; p = 0.027). A significant main effect of time was observed for both tendon thickness (p < 0.001; η2 p = 0.629) and the 5-RM leg extension test (p < 0.001; η2 p = 0.739), with both groups showing progressive improvements over time. Nevertheless, as trend toward a statistically significant time·supplementation interaction was observed (p = 0.099; η2p = 0.126), with an increase in performance only in CMJ in MID vs PRE (36.8  cm (33.8-39.7) vs 34.3  cm (30.8-37.7); p = 0.019) and POST vs MID (POST: 37.6  cm (33.5-41.8); p = 0.015). CONCLUSIONS: A physical rehabilitation program involving eccentric training, stretching, and ESWT is effective in reducing tendon thickness and increasing muscle strength. However. It seems that the addition of CR induces an earlier reduction of pain and a positive effect on CMJ performance. Therefore, CR could be considered as an ergogenic recovery aid in athletes with PT.

Humans↗

PubMed2007

Effects of an intrahospital exercise program intervention for children with leukemia.

PURPOSE: The purpose was to investigate the effect of a 16-wk intrahospital supervised conditioning program including both resistance and aerobic training and a 20-wk detraining period on measures of aerobic fitness, muscular strength, functional mobility, ankle range of motion, and quality of life (QOL) in children receiving treatment for acute lymphoblastic leukemia (ALL). METHODS: Seven children (four boys, three girls; age: 5.1 +/- 1.2 yr, body mass: 24.0 +/- 5.8 kg, height: 114.6 +/- 7.7 cm) in the maintenance phase of treatment against ALL performed three sessions per week for 16 wk of resistance (one set of 8-15 repetitions of 11 exercises) and aerobic training (30 min at > 70% HRmax) followed by 20 wk of detraining where no structured exercise program was performed. Before training, after training, and after detraining, a treadmill test determining .VO2peak and ventilator threshold (VT), muscular strength (6RM), functional mobility (timed up and down stairs test, time up and go 3-m and 10-m tests), passive and dynamic ankle range of motion, and self-reported quality of living were determined. RESULTS: After training, significant increases in .VO2peak, VT, upper- and lower-body muscular strength, and all measures of functional mobility were shown (P < 0.05). Muscular strength was well maintained (significantly greater than before training and no significant decrease from after training) during detraining, whereas .VO2peak, VT, and functional mobility (not significantly different from before training but no significant decrease from after training) were only partially retained. CONCLUSION: Young children in the maintenance phase of treatment against ALL can safely perform both aerobic and resistance training. Training results in significant increases in measures of aerobic fitness, strength, and functional mobility. During detraining, strength and functional mobility are well maintained, whereas .VO2peak and VT are partially maintained.

Child↗

PubMed2006

Physical activity during treatment in children with leukemia: a pilot study.

The purpose of this pilot study was to measure physical activity (PA) levels in children undergoing treatment for acute lymphoblastic leukemia (ALL) and to compare the results with those from age-matched healthy children. We used the MTI Actigraph accelerometer to determine PA (during a 1 week period) in children (n = 7; age = 4-7 y) undergoing maintenance treatment for ALL and in age-matched controls (n = 7). The number of children accumulating at least 60 min of moderate-to-vigorous physical activity (MVPA) for 5 or more days of the week was 3 for the control group, whereas no children with ALL met this criterion. Significantly lower levels of total weekly time of MVPA were seen in children being treated for ALL (328 +/- 107 min) than in controls (506 +/- 175 min) (p < 0.05). When weekday data was analyzed, the ALL patients also had significantly lower mean daily times of MVPA (49 +/- 23 min vs. 79 +/- 25 min). It is thus important that young ALL sufferers are encouraged to participate in appropriate sports, games, and physical activities both in the family and school environments that will prime them with positive attitudes to PA during the critical early years of life.

Antineoplastic Agents↗

PubMed2006

Physiological characteristics of the best Eritrean runners-exceptional running economy.

Despite their young age, limited training history, and lack of running tradition compared with other East African endurance athletes (e.g., Kenyans and Ethiopians), male endurance runners from Eritrea have recently attained important running successes. The purposes of our study were (i) to document the main physical and physiological characteristics of elite black Eritrean distance runners (n = 7; age: 22 +/- 3 years) and (ii) to compare them with those of their elite white Spanish counterparts. For this second purpose we selected a control group of elite Spanish runners (n = 9; 24 +/- 2 years), owing to the traditionally high success of Spanish athletes in long-distance running compared with other white runners, especially in cross-country competitions. The subjects' main anthropometric characteristics were determined, together with their maximum oxygen uptake (VO2 max) and VO2 (mL.kg(-1).min(-1)), blood lactate, and ammonia concentrations while running at 17, 19, or 21 km.h(-1). The body mass index (18.9 +/- 1.5 kg.m(-2)) and maximal calf circumference (30.9 +/- 1.5 cm) was lower in Eritreans than in Spaniards (20.5 +/- 1.7 kg.m(-2) and 33.9 +/- 2.0 cm, respectively) (p < 0.05 and p < 0.01, respectively) and their lower leg (shank) length was longer (44.1 +/- 3.0 cm vs. 40.6 +/- 2.7 cm, respectively) (p < 0.05). VO2 max did not differ significantly between Eritreans and Spaniards (73.8 +/- 5.6 mL.kg(-1).min(-1) vs. 77.8 +/- 5.7 mL.kg(-1).min(-1), respectively), whereas the VO2 cost of running was lower (p < 0.01) in the former (e.g., 65.9 +/- 6.8 mL.kg(-1).min(-1) vs. 74.8 +/- 5.0 mL.kg(-1).min(-1) when running at 21 km.h(-1)). Our data suggest that the excellent running economy of Eritreans is associated, at least partly, with anthropometric variables. Comparison of their submaximal running cost with other published data suggests that superior running economy, rather than enhanced aerobic capacity, may be the common denominator in the success of black endurance runners of East African origin.

Adult↗

PubMed2006

Does creatine supplementation improve functional capacity in elderly women?

The purpose of this study was to determine the effects of short-term (7 days) oral creatine supplementation (0.3 g.kg(-1)) in elderly women during exercise tests that reflect functional capacity during daily living tasks. We assessed several indices of endurance capacity (1-mile walk test, gross mechanical efficiency, ventilatory threshold, and peak oxygen intake determined during cycle-ergometry) and lower-extremity functional performance (time to complete sit-stand test). Subjects were assigned to a creatine (n = 10; age 67 +/- 6 years) or placebo (n = 6; age 68 +/- 4 years) group. We found a significant improvement only after creatine loading in the sit-stand test (placebo: 9.7 +/- 0.9 seconds for pretest and 9.3 +/- 0.7 seconds for posttest, p > 0.05; creatine: 10.0 +/- 0.7 seconds for pretest and 8.8 +/- 1.1 seconds for posttest). Significance was recorded at p < 0.05 for the interaction effect (group [creatine, placebo] x time [pretest, posttest]). In elderly women, short-term oral creatine supplementation does not improve endurance capacity but increases the ability to perform lower-body functional living tasks involving rapid movements.

Activities of Daily Living↗

PubMed2006

Is cardiorespiratory fitness related to quality of life in survivors of breast cancer?

The purpose of this study was to investigate whether indices of cardiorespiratory fitness are related to quality of life (QOL) in women survivors of breast cancer. Using the European Organization for Research and Treatment of Cancer QLQ-30 questionnaire, we assessed the QOL of 16 participants (age, 50 +/- 9 years; body mass, 66.6 +/- 9.6 kg). All participants performed incremental cycle ergometer exercise to determine several indices of cardiorespiratory fitness (e.g., peak oxygen uptake [.V(O2)peak, in L.min(-1), ml.kg(-1).min(-1)]), peak power output (PPO, in W), PPO/ body mass (W.kg(-1), peak heart rate (HRpeak, b.min(-1), peak ventilation (VEpeak), and .V(O2) and heart rate (HR) at the ventilatory (VT) and respiratory compensation (RCT) thresholds. Relationships between QOL and variables were assessed using Spearman rank-difference correlation tests. A significant inverse relationship (p < 0.05) was found for QOL scores and values for age (years) and body mass (kg) ( = -0.53), %HRpeak@VT ( = -0.59) and %VEpeak@VT ( = -0.61). A significant positive relationship (p < 0.05) was found for QOL and PPO/body mass ( = 0.59) and HRpeak ( = 0.78), .V(O2)@RCT (ml.kg(-1.min(-1) ( = 0.51), power output (PO, expressed as either W or W.kg(-1) at RCT, and HR at RCT ( = 0.54). No other significant relationship was found between QOL and variables obtained from the tests. In conclusion, these findings highlight possible relationships between cardiorespiratory fitness and well-being in survivors of breast cancer. From a practical point of view, our data emphasize the need for this population to engage in programmed cardiorespiratory exercise training, mainly designed to improve VT and RCT. The improvement of both submaximal indices can have a beneficial effect on QOL.

Age Factors↗

PubMed2005

PPARGC1A genotype (Gly482Ser) predicts exceptional endurance capacity in European men.

Animal and human data indicate a role for the peroxisome proliferator-activated receptor-gamma coactivator 1alpha (PPARGC1A) gene product in the development of maximal oxygen uptake (V(O2 max)), a determinant of endurance capacity, diabetes, and early death. We tested the hypothesis that the frequency of the minor Ser482 allele at the PPARGC1A locus is lower in World-class Spanish male endurance athletes (cases) [n = 104; mean (SD) age: 26.8 (3.8) yr] than in unfit United Kingdom (UK) Caucasian male controls [n = 100; mean (SD) age: 49.3 (8.1) yr]. In cases and controls, the Gly482Ser genotype met Hardy-Weinberg expectations (P > 0.05 in both groups tested separately). Cases had significantly higher V(O2 max) [73.4 (5.7) vs. 29.4 ml x kg(-1) x min(-1) (3.8); P < 0.0001] and were leaner [body mass index: 20.6 (1.5) vs. 27.6 kg/m2 (3.9); P < 0.0001] than controls. In unadjusted chi2 analyses, the frequency of the minor Ser482 allele was significantly lower in cases than in controls (29.1 vs. 40.0%; P = 0.01). To assess the possibility that genetic stratification could confound these observations, we also compared Gly482Ser genotype frequencies in Spanish (n = 164) and UK Caucasian men (n = 381) who were unselected for their level of fitness. In these analyses, Ser482 allele frequencies were very similar (36.9% in Spanish vs. 37.5% in UK Caucasians, P = 0.83), suggesting that confounding by genetic stratification is unlikely to explain the association between Gly482Ser genotype and endurance capacity. In summary, our data indicate a role for the Gly482Ser genotype in determining aerobic fitness. This finding has relevance from the perspective of physical performance, but it may also be informative for the targeted prevention of diseases associated with low fitness such as Type 2 diabetes.

Adult↗

PubMed2005

Frequency of the C34T mutation of the AMPD1 gene in world-class endurance athletes: does this mutation impair performance?

The C34T mutation in the gene encoding for the skeletal muscle-specific isoform of AMP deaminase (AMPD1) is a common mutation among Caucasians (i.e., one of five individuals) that can impair exercise capacity. The purpose of this study was twofold. First, we determined the frequency distribution of the C34T mutation in a group of top-level Caucasian (Spanish) male endurance athletes (cyclists and runners, n = 104). This group was compared with randomly selected Caucasian (Spanish) healthy (asymptomatic) nonathletes (n = 100). The second aim of this study was to compare common laboratory indexes of endurance performance (maximal oxygen uptake or ventilatory thresholds) within the group of athletes depending on their C34T AMPD1 genotype. The frequency of the mutant T allele was lower (P < 0.05) in the group of athletes (4.3%) compared with controls (8.5%). On the other hand, indexes of endurance performance did not differ (P > 0.05) between athlete carriers or noncarriers of the C34T mutation (e.g., maximal oxygen uptake 72.3 +/- 4.6 vs. 73.5 +/- 5.9 ml.kg(-1).min(-1), respectively). In conclusion, although the frequency distribution of the mutant T allele of the AMPD1 genotype is lower in Caucasian elite endurance athletes than in controls, the C34T mutation does not significantly impair endurance performance once the elite-level status has been reached in sports.

AMP Deaminase↗

PubMed2005

How do endurance runners actually train? Relationship with competition performance.

PURPOSE: To quantify the relationship between total training load and running performance during the most important competitions of the season (national cross-country championships, 4.175- and 10.130-km races). METHODS: Eight well-trained, subelite endurance runners (age (mean+/-SD): 23+/-2 yr; VO2max: 70.0+/-7.3 mL.kg.min) performed a maximal cardiorespiratory exercise test before the training period to determine ventilatory threshold (VT) and respiratory compensation threshold (RCT). Heart rate was continuously recorded using telemetry during each training session over a 6-month macrocycle, designed to achieve peak performance during the aforementioned cross-country races, lasting from late August to the time that these races were held, that is, mid-February. This allowed us to quantify the total cumulative time spent in three intensity zones calculated as zone 1 (low intensity, lower than the VT); zone 2 (moderate intensity, between VT and RCT); and zone 3 (high intensity, above the RCT). RESULTS: Total training time in zone 1 (4581+/-979 min) was significantly higher (P<0.001) than that accumulated in zones 2 (1354+/-583 min) and 3 (487+/-154 min). Total time in zone 2 was significantly higher than time in zone 3 (P<0.05). A correlation coefficient of r=-0.79 (P=0.06) and r=-0.97 (P=0.008) was found between the total training time spent in zone 1 and performance time during the short and long cross-country races, respectively. CONCLUSIONS: Our findings suggest that total training time spent at low intensities might be associated with improved performance during highly intense endurance events, especially if the event duration is approximately 35 min. Interventional studies (i.e., improving or reducing training time in zone 1) are needed to corroborate our findings and to elucidate the physiological mechanisms behind them.

Adaptation, Physiological↗

PubMed2004

In professional road cyclists, low pedaling cadences are less efficient.

PURPOSE: To determine the effects of changes in pedaling frequency on the gross efficiency (GE) and other physiological variables (oxygen uptake (VO2), HR, lactate, pH, ventilation, motor unit recruitment estimated by EMG) of professional cyclists while generating high power outputs (PO). METHODS: Following a counterbalanced, cross-over design, eight professional cyclists (age (mean +/- SD): 26 +/- 2 yr, VO2max: 74.0 +/- 5.7 mL x kg x min) performed three 6-min bouts at a fixed PO (mean of 366 +/- 37 W) and at a cadence of 60, 80, and 100 rpm. RESULTS: Values of GE averaged 22.4 +/- 1.7, 23.6 +/- 1.8 and 24.2 +/- 2.0% at 60, 80, and 100 rpm, respectively. Mean GE at 100 rpm was significantly higher than at 60 rpm (P < 0.05). Similarly, mean values of VO2, HR, rates of perceived exertion (RPE), lactate and normalized root-mean square EMG (rms-EMG) in both vastus lateralis and gluteus maximum muscles decreased at increasing cadences. CONCLUSIONS: In professional road cyclists riding at high PO, GE/economy improves at increasing pedaling cadences.

Adult↗