Ibáñez Santos, Javier

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https://academica-e.unavarra.es/handle/2454/49260

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Ibáñez Santos

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Javier

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Ciencias de la Salud

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750871

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811880

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2009 - 200922010 - 20121
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Author: Izquierdo Redín, Mikel ×

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Now showing 1 - 3 of 3
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    PublicationOpen Access
    Energy metabolism during repeated sets of leg press exercise leading to failure or not
    (Public Library of Science, 2012) Gorostiaga Ayestarán, Esteban; Navarro Amezqueta, Ion; Calbet, José A. L.; Hellsten, Ylva; Cusso, Roser; Guerrero, Mario; Granados, Cristina; González Izal, Miriam; Ibáñez Santos, Javier; Izquierdo Redín, Mikel; Ciencias de la Salud; Osasun Zientziak
    This investigation examined the influence of the number of repetitions per set on power output and muscle metabolism during leg press exercise. Six trained men (age 3466 yr) randomly performed either 5 sets of 10 repetitions (10REP), or 10 sets of 5 repetitions (5REP) of bilateral leg press exercise, with the same initial load and rest intervals between sets. Muscle biopsies (vastus lateralis) were taken before the first set, and after the first and the final sets. Compared with 5REP, 10REP resulted in a markedly greater decrease (P,0.05) of the power output, muscle PCr and ATP content, and markedly higher (P,0.05) levels of muscle lactate and IMP. Significant correlations (P,0.01) were observed between changes in muscle PCr and muscle lactate (R2 = 0.46), between changes in muscle PCr and IMP (R2 = 0.44) as well as between changes in power output and changes in muscle ATP (R2 = 0.59) and lactate (R2 = 0.64) levels. Reducing the number of repetitions per set by 50% causes a lower disruption to the energy balance in the muscle. The correlations suggest that the changes in PCr and muscle lactate mainly occur simultaneously during exercise, whereas IMP only accumulates when PCr levels are low. The decrease in ATP stores may contribute to fatigue.
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    PublicationOpen Access
    The relationship of serum osteocalcin concentration to insulin secretion, sensitivity, and disposal with hypocaloric diet and resistance training
    (Oxford University Press, 2009) Fernández-Real, Jose Manuel; Izquierdo Redín, Mikel; Ortega, Francisco B.; Gorostiaga Ayestarán, Esteban; Gómez-Ambrosi, Javier; Moreno-Navarrete, Jose María; Frühbeck, Gema; Martínez Labari, Cristina; Idoate, Fernando; Salvador, Javier; Forga, Lluís; Ricart, Wifredo; Ibáñez Santos, Javier; Ciencias de la Salud; Osasun Zientziak
    Context: Bone has recently been described as exhibiting properties of an endocrine organ by producing osteocalcin that increases insulin sensitivity and secretion in animal models. Objective and Design: We aimed to evaluate circulating osteocalcin in association with insulin sensitivity and insulin secretion in three different studies in nondiabetic subjects: one cross-sectional study in 149 men (using minimal model), and two longitudinal studies in two independent groups (one formed by 26 women, and the other by 9 men and 11 women), after a mean of 7.3 and 16.8% weight loss, and after a mean of 8.7% weight loss plus regular exercise. Results: In the cross-sectional study, circulating osteocalcin was associated with insulin sensitivity, mainly in lean subjects, and with insulin secretion (only in lean subjects). A mean of 16.8%, but not 7.3% weight loss, led to significant increases in circulating osteocalcin. However, a mean of 8.7% weight loss plus regular exercise led to the more pronounced effects on the serum osteocalcin concentration, which increased in parallel to reduced visceral fat mass, unchanged thigh muscle mass, and increased leg strength and force. The postintervention serum levels of osteocalcin were associated with both insulin sensitivity (r = 0.49; P = 0.03) and fasting triglycerides (r = −0.54; P = 0.01). The change in visceral fat was the parameter that best predicted the change in serum osteocalcin, once age, body mass index, and insulin sensitivity changes were controlled for (P = 0.002). Conclusion: Circulating osteocalcin could mediate the role of bone as an endocrine organ in humans.
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    PublicationOpen Access
    Circulating soluble transferrin receptor concentration decreases after exercise-induced improvement of insulin sensitivity in obese individuals
    (Springer Nature, 2009) Fernández-Real, Jose Manuel; Izquierdo Redín, Mikel; Moreno-Navarrete, Jose María; Gorostiaga Ayestarán, Esteban; Ortega, Francisco B.; Martínez Labari, Cristina; Idoate, Fernando; Ricart, Wifredo; Ibáñez Santos, Javier; Ciencias de la Salud; Osasun Zientziak
    Background: Circulating soluble transferrin receptor (sTfR) has been recently found to be associated negatively with insulin sensitivity. Objective: To evaluate circulating sTfR concentration after changing insulin sensitivity in obese individuals. Design: Circulating sTfR concentration was evaluated after diet-induced weight loss in obese women (diet (D) group, n=8); after diet-induced weight loss plus resistance training (D+RT group, n=11); and after follow-up without weight loss (control (C) group, n=7). Results: After 16 weeks, insulin sensitivity (HOMA (Homeostasis Model Assessment) value) significantly improved in parallel to weight loss (−7.3%) and reduced total fat mass (evaluated using magnetic resonance imaging) in the D group. Thigh muscle mass decreased significantly (P=0.03). Serum sTfR concentration did not change significantly. In the D+RT group, weight loss (−8.7%) and improvement of insulin sensitivity were of similar magnitude. Thigh muscle mass was preserved (P=0.8). Serum sTfR concentration decreased significantly (P=0.001). Interestingly, higher the thigh muscle volume after weight loss, higher the decrease in circulating sTfR concentration. We also found that higher the increases in leg force at week 16, higher the decrease in circulating sTfR concentration in all individuals as a whole. No significant changes were observed in insulin sensitivity, sTfR concentration or thigh muscle mass in the C group. Conclusion: These findings suggest a long-term regulation of serum sTfR concentration by exercise-induced improvement of insulin ensitivity in obese individuals.