Issue with ADXL345 free fall threshold

I am using Arduino Uno and ADXL345 to detect free fall movement as a part of my project.
This is my pin connection
ADXL345 UNO
INT1 - D2
VCC , CS - 3.3v
SCL - A5
SDA - A4

This is my sample code.

#include <Wire.h>
#include <ADXL345.h>
ADXL345 adxl; //variable adxl is an instance of the ADXL345 library

 void setup(){
           Serial.begin(9600);
          adxl.powerOn();

          adxl.setFreeFallThreshold(10); 
          adxl.setFreeFallDuration(10); 
 
          adxl.setInterruptMapping( ADXL345_INT_FREE_FALL_BIT,ADXL345_INT1_PIN );
          adxl.setInterrupt( ADXL345_INT_FREE_FALL_BIT,  1);
}

void loop(){
          int x,y,z;  
          adxl.readAccel(&x, &y, &z); 
          Serial.print(x);
          Serial.print("\t");
          Serial.print(y);
          Serial.print("\t");
          Serial.println(z);
         
          byte interrupts = adxl.getInterruptSource();
          // freefall
          if(adxl.triggered(interrupts, ADXL345_FREE_FALL)){
                    Serial.println("freefall");
          } 
          delay(100);
 }

I set the threshold value as 10, as a test value. I want to figure out the exact threshold value for a fall movement. But I cannot find the relationship between my test threshold value and x,y,z data from the sample data set I got(mentioned below).

I got a sample data set for the movement of Standing up from the sitting position.
x y z
78 16 194
72 10 213
36 6 271
71 -18 281
0 31 258
12 28 269
15 22 221
40 12 168
Freefall
30 18 103
Freefall
29 12 152
Freefall
45 -6 160
57 -22 215
13 13 205
71 -16 190
45 -12 209

I did some Google searching but didn’t find any explanation. Could you please explain the relation between my x,y,z data and my test threshold value?