Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:

Many Cancer Trial Participants Overly Optimistic: Study

Unrealistic optimism is common among patients in early phase clinical cancer trials, according to a new study.

U.S. researchers looked the responses of 72 adults enrolled in cancer studies in the New York area who were interviewed about their expectations regarding risks and benefits, United Press International reported.

"We found a significant optimistic bias in their responses," wrote Lynn A. Jansen, of Oregon Health and Sciences University, and colleagues.

"Respondents tended to overestimate the benefits of the trial they were enrolled in and underestimate its risks. In addition, we found no significant relationship between respondents' understanding of the trial's purpose and how susceptible they were to unrealistic optimism. Our findings suggest that improving the consent process for oncology studies requires more than addressing deficits in understanding," the researchers said, UPI reported.

The study appears in the journal IRB: Ethics & Human Research.

-----

University of Iowa Football Players Hospitalized With Muscle Condition

Thirteen University of Iowa football players remain in hospital after being diagnosed with a muscle syndrome that can cause kidney damage.

Rhabdomyolysis occurs when muscles break down and release a protein called myoglobin, which can travel through the bloodstream and harm the kidneys.

At a press conference this week, a university spokesman said it's not known how the athletes developed the condition, ABC News reported. Intense exercise, dietary supplements and certain medications can cause rhabdomyolysis.

The university's director of football operations, Paul Federici, told reporters at the press conference that he didn't know the exact structure of the football players' workouts, but noted that they were given breaks and provided with plenty of water, ABC News reported.

-----

Mandela Released From Hospital

Nelson Mandela was discharged from hospital Friday after being treated for an acute respiratory infection, said South Africa's surgeon general.

Doctors are pleased with Mandela's recovery and the 92-year-old anti-apartheid hero and former president of South Africa will continue to receive treatment at home, said Surgeon General V.J. Ramlakan, CNN reported.

"We may recall that he suffered from tuberculosis and has had previous respiratory infections," Ramlakan said. "He is also not as mobile as before. And over the last few years, has had to be assisted with movement."

News of Mandela's hospitalization caused concern worldwide, CNN reported.

-----

First Lady Praises Military's Fitness and Nutrition Programs

The U.S. military's new emphasis on exercise and healthy eating for recruits could be a model for improving fitness and nutrition among young people across the nation, according to Michelle Obama.

The first lady got a personal look at the military's efforts Thursday when she visited the Army's largest training post at Fort Jackson, S.C., the Associated Press reported.

"I am fascinated by what you're doing," Obama told Lt. Gen. Mark Hertling, who created new diet and exercise programs that include routines for core body strength and stamina and more dark greens, whole grains and no-fat milk in mess halls.

Obama said that poor fitness is "not just a health issue but a national security issue," the AP reported.

-----