Learn the breakthrough in handball: after the feint go past the defender, protect the ball and finish securely against the goalkeeper without a foul.
The breakthrough is getting into the space beside the defender until you have a free chance against the goalkeeper. It starts with a feint, uses your 3 permitted steps [1] and ends in a shot or a pass to the pivot. There is the straight and the curved breakthrough.
The honest answer to "How good is the chance after a breakthrough?": Very good if you are truly free. At the 2015 World Championship, shots in a counter-attack situation where the defence was outnumbered and the attacker faced the goalkeeper alone ("breakthroughs" in the study) went in 80% of the time (564 of 704), fast breaks 79%. Shots from 9 metres were far less successful at 37% [2]. Note: that was not a classic breakthrough against a set defence; the study means shots after winning the ball with 2 to 5 passes [2]. But it shows how much more a free lane is worth than a shot from far away.
How long it takes to get to a secure breakthrough depends on where you start; there is no solid study figure for it, that is coaching experience.
The breakthrough does not start with the sprint but with the feint before it.
Stand in the backcourt about 1 to 2 metres in front of the defender, ball at chest height. Look at the space beside him, not at him. Milestone: Standing, you can see on which side of the defender there is more room.
Fake one direction and then go the other way. According to a study of 96 handball players, good fakers show shorter ground contact times, higher speed, a shallower cutting angle and greater cutting width than less skilled ones, plus a quick head movement against the actual direction [3]. That means: fool with speed and shoulder/head, not just the feet. Milestone: In 6 of 10 attempts the defender goes the wrong way.
In the straight breakthrough you go past the defender in a line. In the curved one you run a short arc around him with the ball in the far hand. The arc is longer but protects the ball better. Milestone: You can show both variants from a 5 metre run-up.
Hold the ball on the side away from the defender, with your shoulder between him and the ball. If the defender touches you, stay stable. If you keep control of ball and body after a foul, there is no 7-metre throw and you play on [1]. Milestone: After light contact you stay on your feet and keep the ball in 8 of 10 cases.
Throw after your third step, before the goalkeeper can set himself. Alternatively, pass to the pivot when the goalkeeper and defence come to you. Milestone: 6 of 10 breakthroughs end in a clean shot or pass.
The sprint after the feint is the most dangerous moment for your knee. In a Danish survey of 4,540 injured handball players with ACL tears, 55% of the injuries occurred without contact, 25% during pivoting and 11% in one-legged landings. In 80% of cases the players had the ball, most often while feinting (32%) or shooting (30%) [4]. In a video analysis of 20 ACL tears in women's handball, the most common situation (12 of 20) was a plant step with a change of direction on a nearly straight knee [5]. One study also warns of a possible trade-off: good fakers showed a greater peak knee abduction moment, that is, stronger inward buckling of the knee, across the stance phase [3]. Plant the step with a slightly bent knee over the foot [6]. This guide explains and motivates; it does not replace supervised training or a coach.
Decide only after the first step. If you already know before the sprint whether you will shoot or pass, you are readable. After the first step you see how goalkeeper and defence react. This is practical experience; we have not read a study that measures it.
With a feint that lures the defender to the wrong side, a quick sprint into the gap, a protected ball and a finish within at most 3 steps [1][3].
The straight breakthrough takes the shortest path past the defender. The curved one runs a short arc around him; the ball is better protected but the path longer. Both variants are practice standard.
Only if a clear scoring chance is thereby destroyed. If you keep control of ball and body despite the foul, there is no 7-metre throw and you play on [1].
That depends on the space. At the 2015 World Championship, counter-attack shots with 2 to 5 passes ("breakthroughs") went in 80% of the time, shots from 9 metres 37% [2].
Throwing Feint in Handball: Lure the Goalkeeper Into the Wrong Reaction