The Evolution of World-Class Endurance Training: The Scientist's View on Current and Future Trends.

Background: Elite sport is continuously evolving. World records keep falling and athletes from a longer list of countries are involved.

Purpose: This commentary was designed to provide insights into present and future trends associated with world-class endurance training based on the perspectives, experience, and knowledge of an expert panel of 25 applied sport scientists.

"Living High-Training Low" for Olympic Medal Performance: What Have We Learned 25 Years After Implementation?

Background: Altitude training is often regarded as an indispensable tool for the success of elite endurance athletes. Historically, altitude training emerged as a key strategy to prepare for the 1968 Olympics, held at 2300 m in Mexico City, and was limited to the "Live High-Train High" method for endurance athletes aiming for performance gains through improved oxygen transport. This "classical" intervention was modified in 1997 by the "Live High-Train Low" (LHTL) model wherein athletes supplemented acclimatization to chronic hypoxia with high-intensity training at low altitude.

Comparable Outcomes Between Native and Periprosthetic Fractures of the Distal Femur.

Despite the rising prevalence of arthroplasty and aging population, limited data exist regarding differences in periprosthetic fracture clinical outcomes compared with native counterparts. This study compares differences in hospital treatment, morbidity, and mortality associated with periprosthetic distal femur fractures at an urban level 1 trauma center. We retrospectively reviewed all adult AO/OTA type 33 fractures (526) that presented to our institution between 2009 and 2018.

Medical Care for Swimmers.

Swimming is one of the most popular sports worldwide. Competitive swimming is one of the most watched sports during the Olympic Games. Swimming has unique medical challenges as a result of a variety of environmental and chemical exposures.

Kenyan and Ethiopian distance runners: what makes them so good?

Since the 1968 Mexico City Olympics, Kenyan and Ethiopian runners have dominated the middle- and long-distance events in athletics and have exhibited comparable dominance in international cross-country and road-racing competition. Several factors have been proposed to explain the extraordinary success of the Kenyan and Ethiopian distance runners, including (1) genetic predisposition, (2) development of a high maximal oxygen uptake as a result of extensive walking and running at an early age, (3) relatively high hemoglobin and hematocrit, (4) development of good metabolic "economy/efficiency" based on somatotype and lower limb characteristics, (5) favorable skeletal-muscle-fiber composition and oxidative enzyme profile, (6) traditional Kenyan/Ethiopian diet, (7) living and training at altitude, and (8) motivation to achieve economic success. Some of these factors have been examined objectively in the laboratory and field, whereas others have been evaluated from an observational perspective.

The upper limit of aerobic power in humans.

Data on the upper limit of aerobic power in humans are scarce. Thus, here we demonstrate extraordinarily high V'O(2)max and submaximal exercise performance in a young elite cross country skier (22 years, 170 cm, 63 kg; hemoglobin: 16.8 g/dL) who was evaluated before winning an Olympic gold medal.

Hematological and physiological adaptations following 46 weeks of moderate altitude residence.

Although acclimatization to moderate altitude (MA) is thought to be unnecessary or to require minimal adaptation, retrospective data from the U.S. Air Force Academy (USAFA), a military college located at 2210 m, suggested otherwise.

Long-term monitoring shows hepatitis B virus resistance to entecavir in nucleoside-naïve patients is rare through 5 years of therapy.

Unlabelled: Patients with chronic hepatitis B virus (HBV) infection who develop antiviral resistance lose benefits of therapy and may be predisposed to further resistance. Entecavir (ETV) resistance (ETVr) results from HBV reverse transcriptase substitutions at positions T184, S202, or M250, which emerge in the presence of lamivudine (LVD) resistance substitutions M204I/V +/- L180M. Here, we summarize results from comprehensive resistance monitoring of patients with HBV who were continuously treated with ETV for up to 5 years.

Early hepatitis B virus DNA reduction in hepatitis B e antigen-positive patients with chronic hepatitis B: A randomized international study of entecavir versus adefovir.

Unlabelled: This study was undertaken to compare the early antiviral activity and viral kinetic profiles of entecavir (ETV) versus adefovir (ADV) in hepatitis B e antigen positive nucleoside-naïve adults with chronic hepatitis B (CHB). Sixty-nine nucleoside-naïve CHB patients with baseline HBV DNA of 10(8) copies/mL or more were randomized 1:1 to open-label treatment with entecavir 0.5 mg/day or adefovir 10 mg/day for a minimum of 52 weeks.

Physical fitness and hematological changes during acclimatization to moderate altitude: a retrospective study.

While high altitude adaptations have been studied extensively, limited research has examined moderate altitude (MA: 1500 to 3000 m) adaptations and their time course, despite the fact that millions of people sojourn to or reside at MA. We retrospectively examined long-term MA acclimatization by analyzing recurring physical fitness test results and hematological data among 2147 college-age male cadets previously residing at either sea level (SL) or MA and currently attending the U.S.

Application of altitude/hypoxic training by elite athletes.

At the Olympic level, differences in performance are typically less than 0.5%. This helps explain why many contemporary elite endurance athletes in summer and winter sport incorporate some form of altitude/hypoxic training within their year-round training plan, believing that it will provide the "competitive edge" to succeed at the Olympic level.

Effect of hypoxic "dose" on physiological responses and sea-level performance.

Live high-train low (LH+TL) altitude training was developed in the early 1990s in response to potential training limitations imposed on endurance athletes by traditional live high-train high (LH+TH) altitude training. The essence of LH+TL is that it allows athletes to "live high" for the purpose of facilitating altitude acclimatization, as manifest by a profound and sustained increase in endogenous erythropoietin (EPO) and ultimately an augmented erythrocyte volume, while simultaneously allowing athletes to "train low" for the purpose of replicating sea-level training intensity and oxygen flux, thereby inducing beneficial metabolic and neuromuscular adaptations. In addition to "natural/terrestrial" LH+TL, several simulated LH+TL devices have been developed to conveniently bring the mountain to the athlete, including nitrogen apartments, hypoxic tents, and hypoxicator devices.

Introduction to altitude/hypoxic training symposium.

Altitude/hypoxic training has traditionally been an intriguing and controversial area of research and sport performance. This controversial aspect was evident recently in the form of scholarly debates in highly regarded professional journals, as well as the World Anti-Doping Agency's (WADA) consideration of placing "artificially-induced hypoxic conditions" on the 2007 Prohibited List of Substances/Methods. In light of the ongoing controversy surrounding altitude/hypoxic training, this symposium was organized with the following objectives in mind: 1) to examine the primary physiological responses and underlying mechanisms associated with altitude/hypoxic training, including the influence of genetic predisposition; 2) to present evidence supporting the effect of altitude/hypoxic acclimatization on both hematological and nonhematological markers, including erythrocyte volume, skeletal muscle-buffering capacity, hypoxic ventilatory response, and physiological efficiency/economy; 3) to evaluate the efficacy of several contemporary simulated altitude modalities and training strategies, including hypoxic tents, nitrogen apartments, and intermittent hypoxic exposure (IHE) or training, and to address the legal and ethical issues associated with the use of simulated altitude; and 4) to describe different altitude/hypoxic training strategies used by elite-level athletes, including Olympians and military special forces.

Entecavir versus lamivudine for patients with HBeAg-negative chronic hepatitis B.

Background: Entecavir is a potent and selective antiviral agent that has demonstrated efficacy in phase 2 studies in patients with hepatitis B e antigen (HBeAg)-negative chronic hepatitis B.

Methods: In this phase 3, double-blind trial, we randomly assigned 648 patients with HBeAg-negative chronic hepatitis B who had not previously been treated with a nucleoside analogue to receive 0.5 mg of entecavir or 100 mg of lamivudine once daily for a minimum of 52 weeks.

A comparison of entecavir and lamivudine for HBeAg-positive chronic hepatitis B.

Background: Entecavir is a potent and selective guanosine analogue with significant activity against hepatitis B virus (HBV).

Methods: In this phase 3, double-blind trial, we randomly assigned 715 patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B who had not previously received a nucleoside analogue to receive either 0.5 mg of entecavir or 100 mg of lamivudine once daily for a minimum of 52 weeks.

Effect of a global alteration of running technique on kinematics and economy.

In this study, we examined the consequences of a global alteration in running technique on running kinematics and running economy in triathletes. Sixteen sub-elite triathletes were pre and post tested for running economy and running kinematics at 215 and 250 m.min-1.

Treatment of compartment syndrome: transverse fasciotomy as an adjunct to longitudinal dermatofasciotomy: an in vitro study.

Objective: This study describes a previously unpublished technique for compartment release that combines adjunctive transverse fasciotomies with a limited longitudinal dermatofasciotomy and compares its efficacy with a standard extensile longitudinal dermatofasciotomy.

Design: Limited 10-cm longitudinal dermatofasciotomies were performed bilaterally on 14 cadaveric specimens (28 legs). Next, we performed transverse fasciotomies on 1 limb and performed extensions of the longitudinal incision on the contralateral limb.

Atazanavir plus ritonavir or saquinavir, and lopinavir/ritonavir in patients experiencing multiple virological failures.

Objective: To evaluate atazanavir/ritonavir (ATV/RTV) (300/100 mg) once daily, atazanavir/saquinavir (ATV/SQV) (400/1200 mg) once daily, and lopinavir/ritonavir (LPV/RTV) (400/100 mg) twice daily, each with tenofovir (300 mg) once daily and a nucleoside reverse transcriptase inhibitor in treatment-experienced HIV-infected patients.

Methods: Randomized, open-label, 48-week multicenter trial of 358 randomized adult patients who had failed two or more prior HAART regimens with baseline HIV RNA > or = 1000 copies/ml and CD4 cell count > or = 50 x 10(6) cells/l.

Results: The primary efficacy endpoint [plasma HIV RNA reduction assessed by time-averaged difference (TAD)] was similar for ATV/RTV and LPV/RTV [TAD 0.

Subtrochanteric fixation stability depends on discrete fracture surface points.

Fixation of subtrochanteric femur fractures may present complications, including malunion, delayed union, or nonunion, and is thought to be related to early fracture stability. To examine the initial stability of subtrochanteric fracture fixation, we investigated construct stiffness, interfragmentary gaps, and overall and point-wise interfragmentary motion (ie, axial and shear displacements) in synthetic composite femurs fixed with a cephalomedullary nail or condylar blade plate. Simulated stable and unstable subtrochanteric femur fractures were created in composite femurs, anatomically reduced, fixed with either a long Gamma nail or a blade plate, and subjected to combined axial, bending, and torsional loading.