requête SQL: 
$mysql3 = SELECT id_balade, SUM( TIME_TO_SEC( temps ) ) AS cumul
FROM (

SELECT id_balade AS id_balade, min( date ) AS heure_depart, max( date ) AS heure_arrivee, timediff( max( date ) , min( date ) ) AS temps
FROM pts_gpx
GROUP BY id_balade, cast( date AS date )
) AS balade_temps
WHERE id_balade =118
GROUP BY id_balade

$tab_duree = mysql_fetch_array($mysql3);

//requête
$mysql =mysql_query('SELECT * FROM matable where id = 118 ');
//on met tout dans un tableau
$retour = mysql_fetch_array($mysql);

//puis on récupère ce qu'on veut

$madonnee = $retour['mon_champ'];

//on peut afficher la donnée :
echo $madonnee;

$retour = mysql_query('SELECT * FROM balade WHERE id=\'' . $id_balade . '\'');
	
while ($donnees = mysql_fetch_array($retour))

{
}